Ok here's my take, it's likely I'm not any stronger than you are so take this 'advice' with a pinch of salt.
1) I believe opening study can be extremely benificial if the rule "wide, not deep" is followed and the emphasis is on understanding the positions and not on memorizing variations. I don't have a repertoire, I play almost anything. The result is that I have an elementary knowledge of a wide variety of positions and can often feel my way through in lines where I have no specific knowledge (obviously a lack of specific knowledge has its pitfalls in certain instances also). A drawback to this approach is I spend a lot of time in the opening where if I concentrated on developing a steady repertoire I could be quicker and more confident.
2) Tactics schmactics. Playing games will give you all the tactical training you need. I've never done any tactics training except for 5 minutes on chesstempo every couple of weeks or so and a few CT-Art problems every now and then. A better approach to tactics training is to use a book of annotated games arranged around a particular tactical theme. Minev's "Mastering Tactical Ideas" is a good one.
3) I don't believe this deserves a seperate point. Middlegame = Tactics + Position
4) Kmoch "Pawn Power in Chess" (must read), Soltis "Pawn Structure Chess", Stean "Simple Chess", anything by Dvoretsky/Yusupov. And annotated games collections where the annotations are of an explanatory style rather than variation trees, Bronstein "Zurich 1953" and books that are annotated by the players themselves (Botvinniks books especially) are good for this.
5) Anyone who finds endgames boring isn't doing it right. Learn to love endgames, Shereshevsky "Endgame Strategy" and Karolyi "Endgame Virtuoso" will help. Start by mastering simple king+pawn endings if you haven't already. Get a good book on rook+pawn endings (there are plenty, I'll recommend Minev again). The study you do for the positional side of your game will help with minor piece endings. Again, anything by Dvoretsky and/or Yusupov is gold (although "Endgame Manual" is purely theoretical and should be reserved for when you've developed a healthy thirst for endgames)
6) Learn to calculate properly. This is the tricky part and if you find out how, let me know.
In the past, I have observed many high-rated players discourage opening studies in favor of improving in other areas of chess (ie. dropping fewer pieces, missing fewer tactics, improving positional play). What is the most effective way to do so? I have tried everything from grinding on tactics, reading through annotated games, attempting to annotate others' games, and playing a whole ton of chess. I'm not complaining about the effectiveness of what I've done, I'm just curious if others have suggestions as to what is best to work on so I can better direct my studies.
In his book, Chess Fundamentals, Capablanca wrote that one ought to master endgames first, middlegames second, and openings last. However, that was before everyone had a near-infinite supply of tactics workouts on magical little boxes that display words, pictures, and chess diagrams (yes, the computer!).
The original question persists--how should a novice like myself who is lacking in most areas of the game, but not entirely deficient in any, proceed? Indeed I drop pieces, miss tactics, and only on occasion am able to pull off a neat combination. My endgame play is pathetic, considering that most of my wins are the result of a middlegame mate/(or the occasional wipeout when I get materialistically greedy), or a blatantly obvious endgame with a minor/pawns/king versus pawns/a king without a minor.
Finally, what is the most effective way to drive the basics home? I'm willing to get books, scour the internet for masters' games, do "boring" exercises, no problem. Yet, watching a video on the lucena/philador and practicing a couple times against an engine apparently wasn't enough--when I came to an online game where I thought I could transpose into the lucena, I drew because I forgot all of the details and nuances.
In an attempt to answer my own question, here are the possibilities I have come up with:
1) Revamp my opening repertoire. Before all of you jump out of your seats and send chess pieces flying at my head, let me explain. I have rarely ever replied to 1. d4 with 1. ...d5. Perhaps I did when I was just learning how the pieces moved, but that was several years ago, before I took the game seriously. I have tried QID and Nimzo-Indian in the past, and currently play KID against it (although, I can't really call it King's Indian Defense either, as I typically stray from theory in the first five moves, I think). Neither have I ever played the Italian, nor any of the Colle Systems. I have never played 1. d4, except when trying out the London System for a small handful of games. I play e4, tried out the Spanish for a short while, and recently switched to King's Gambit in hopes of improving my tactical eye and combinational skills. I play the Bb5 Sicilian to avoid having to delve into heavy theory (although there is still some to learn, most of my opponents at my level probably know the same amount or less). Against e4, I now regularly play the French, although I have spent quite a bit of time wielding the the Scandinavian as well. In fact, I have even tried out the English, with decent results against a low-leveled pool of competition (conference matches in high school).
Back to this first point. Should I roll a die to randomly determine my first move or something, then play to improve my middlegame? Or perhaps, switch to d4 simply for more experience? Or is my current repertoire okay?
2) Tactics, tactics, tactics. At the beginning of the year, I heard someone tell me that tactics where the fastest way to improve one's chess at the beginner levels. A friend of mine dragged me into chess club this year, and suggested that I try out for the team. Fearful of not making it in, I did tactic puzzles one after another online for about an hour a day, and eventually made it to third board. Later on, I realized that I would often have trouble using all of this new material that I would earn! Two knights and a bishop up, my only hope of winning was stripping the other side bare through tactical play and exchanges, or getting lucky and recognizing a forced mating combination. That brings me to my next point...
3) Middlegame books. I borrowed/bought a ton, and can get more. I watched a few videos and started to read some books on identifying weaknesses in opponents' kingside, elimating defenders, and infiltrating with pieces of my own. By doing so, I've picked up a bit on attacking play (albeit most novices like myself claim the same!), but run into the trouble of "hope chess". Often, I try to calculate attack combinations in my head, then use the analyzer tool to check my work before making the move. Occasionally, I have been guilty of calculating a sacrifice, discovering several working lines, and leaving a blind spot at failed combinations since the combination "looks so fun" when it works (although my calculations were awfully close, and my opponents missed the refutation of such sacrifices in most cases). Obviously, that is bad chess. Part of the problem, though, is the fact that I frequently fail to bring in all of my pieces for the attack. Simply put, more pieces mean more possibilities... bringing us to point 3.
3) Positional play. I honestly have absolutely no idea how to directly improve this aspect of my game, and would walk on a forest of cacti to do so (alright, that's a slight exaggeration). What I have done in the past is go through the Chess Opening Explorer website (At the time, I didn't know chess.com even had one) and find various GM games to follow. I would pick the openings that I played, simply to get a feel for what ideas have been tried in the past with such openings, and try to guess the next move, or at least try to find out why each move was played. Better square? Worse square? When one of your own pieces blocks another or is restricted by other means (edge of the board, opponents pieces, threats, etc.), it's bad. From there, I've been cruising along my foundering ship of common sense and logic.
4) Endgames. Here we are again. Although I am somewhat interested in improving my endgame (I find them deadeningly boring, but what is dessert without dinner?), I am not quite sure where to start. I have dozens of books at my disposal, but I obviously can't read them all at once. The internet and chess engines tend to be experts in this field as well, since the calculations are extremely easy for the computer, relative to other stages of the game where more pieces are present. Knights are better in closed positions, bishops are better when split groups of pawns are present, and pawns are typically best on opposite squares of your bishop. With rooks in the endgame, I am close to hopeless. An IQP position or something of the like is strong when more pieces are on the board (I hope I don't have this one backwards). I've heard of these concepts plenty of times, yet, I have trouble doing these things in practice.
Thank you for making it this far, skimming or not. I'd appreciate any comments and words of advice!