The following are all personal views and should be considered with discernment.
It's been a long time since I've played OTB chess. The easiest way to prepare for a tournament... is not to prepare specifically. Treat it like your usual games, and try to enjoy the event. Maybe if there's a big purse at the end it would be good to put more effort in, but usually you'd do best if you just do what you normally do and relax.
Approaching a tournament is rather different from approaching routine chess study. For one, the priorities are totally flipped: openings become more important than endings for once (since you should have already been studying and internalising endgame ideas and methods regularly.) You already have a foundation of chess skills, and now would be the time to craft ways to demonstrate that knowledge in a game. And to do that would mean an opening repertoire (of sorts, bear in mind you won't stay in theory for long.)
So let's go through your choices:
The main gap in your white repertoire is 1. d4 d5 2. c4 c6 leading not to QGD setups but Slav/Semi-Slav. If you play 2. c4 you need to know the QGA, QGD, Slav and Semi-Slav setups... although it shouldn't matter much at your level. Heck, it never bothered me at mine. Further reading to do perhaps, but don't panic here.
As black, 1. e4 e5 2. f4 is the King's Gambit which you said gave some trouble. Honestly, I have no clue how to deal with this (I play 1. e4 c6, but can get into the KG via 1. f4 e5 2. e4 and I'm clueless.) Try reading up on this classic and instructive opening yourself; lines I've been toying with are accepting 2...exf4 3. Bc4 Qh4+ or 2...exf4 3. Nf3 g5.
And we're ignoring here the massive possibilities of white playing stuff like the Colle, Stonewall, KIA, or London or other stuff. Or indeed the BDG, 3. Bc4 Petroff, Cochrane Gambit or other wacky stuff. Quite simply, an opening repertoire may come in handy, but don't put too much into learning move-orders. Just play sensibly.
Which moves into the next part: the middlegames. In studying your chosen openings I hope you have some idea of the pawn-structures and strategic plans entailing each. Try to steer the game into similar structures you know, and apply some sense to unfamiliar positions. Once again, this is where your routine preparation will pay off: how well do you understand the middlegames? Oh, and importantly, don't hang pieces or overlook tactics (especially your opponent's hanging pieces!)
Endgames you should be familiar with from regular study. I hope. There it's more or less a matter of technique, of course always keeping an eye out for tactics to instantly decide the game if possible.
Clock management seems to be an issue for you? In my own experience, games will typically last 40-50 moves tops, barring those long endgames in which most moves are intuitive. Allocating time to moves is another crucial skill: generally in 30|0 I'd spend no more than 1-2 minutes on a move. Opening moves can be almost blitzed out, so maybe 10 seconds on each (sanity checking and looking out for quick tactics.) On forced moves (only legal move, or only non-losing move - make sure you check it really is!) don't spend much time, just move it. Spending 5 minutes on your only legal move would be frankly ridiculous.
The key is in the transition to middlegame: I can burn about 4-5 minutes considering a long term plan on one move. If you find yourself in a tactical melee, you can also spend longer on that move to work your way through (or work partially through and play the first move of a sequence... and think on your opponent's time.) I've ever spent 20 minutes unravelling a position (sorting out an immediate tactical sequence and a general gameplan following that) then moving quickly the rest of the way to victory.
Time trouble seems to vary by individual. For myself, 5 minutes is where I start to get a little nervous, and <2 minutes is when I enter "panic mode", in which I take no more than 3 seconds per move (buying me another 40 moves.) It may be useful to have your own "panic mode" to avoid losing on time, based on the fastest you can move (with sanity checking) and how much time you feel comfortable with.
Final general tips: Create a good atmosphere for yourself. Eat what you want but not until you're bloated or sleepy, rest between rounds (if you have stamina you can do post-mortems), hydrate yourself regularly, bring you lucky items, and whatever. Also have a confident demeanor no matter what happens on the board, and be left-handed with white.
Good luck!
Hey guys. I have a tournament coming up and I want to ask some questions about how I should prepare.
1) I play 30|0 on chess.com live time control simply because it's the longest time control available. I like to play online chess and I like to play very long games where I can explore a lot of possibilities over a lot of time. The tournament I will be playing in is also 30|0. This is a bit quick for me and I make mistakes in it from time to time because I don't quite feel comfortable without enough time to think. I always feel I'm in time trouble. In my last tournament, we had over two hours of time and I enjoyed it. Is there any advice anyone can give (other than play more 30|0 games because I am doing that anyway) about how to play well in short tournament games? I had a 30|0 live game tonight that was going decently until, with less than ten minutes left on my clock, I missed a good move by my opponent that won two pawns and put me in a really bad position. I feel if I had been playing with more time, I would have been more comfortable and I would have been able to see that. Things like that make me like long chess or online chess.
2) I have recently (i.e. last month and a half) started playing the Queen's Gambit and I will be playing that in this tournament. I am rated U.S.C.F. well below my ratings on here (U.S.C.F. not much above 1000, hoping to increase my rating), although I do believe I am perhaps three hundred points better than my rating given that many of my best chess friends at my chess club are rated in the 1500s and we have relatively even results. How much should I prepare each phase of the game and how? What should I do until the tournament in the new openings I am using, the middlegames, and the endgames?
3) In my last tournament, one opponent (the only of the five I faced who beat me) surprised me by playing the King's Gambit. It made me aware that perhaps I need to look at some weird lines of my openings just in case. What is a simple way to play against the King's Gambit if I see it and what are other weird openings or gambits I need to be aware of that I should actually look at?
Some other information: the tournament is in three weeks, so I do have some time to do this stuff, although mainly only on the weekends since I have a lot of schoolwork on the weekdays. I do not have a chess tutor with whom I could study (I used to) mainly because I have less time now than I used to. My opening repertoire is as follows:
As white:
1. d4
If 1. d4 d5 2. c4 Queen's Gambit main lines (no Catalan or other variants)
If 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 Nimzo-Indian Capablanca variation
If 1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3 Bg7 7. Bc4 Gruenfeld Exchange variation
If 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. f3 0-0 King's Indian Sämisch
If 1. d4 f5 2. Bg5 and trade on f6 hopefully.
If c6, d6, e6 or anything else, I usually play 2. c4 because I don't want to transpose into something my opponent knows better than I do like a French or a Caro-Kann that I don't know very well.
As black:
If 1. e4 e5 2. Nf3 Nf6 Petrov
If 1. d4 d5 2. c4 e6 Orthodox Q.G.D.
If 1. Nf3 Nf6
If 1. c4 c5 and symmetrical English
Thank you for reading my post and helping me prepare for this tournament :)