How to Improve

So, I am trying to get back into chess after a years long hiatus. I wouldn't consider myself a rookie at all, but I think I have gotten rusty at the game.

I want to improve, and so been reading up on a lot of chess content to get better. I think my biggest weaknesses are falling for discovered attacks and checkmating the opponent in inefficient ways.

For the former, I see what looks like a good move, only for it to undermine my position and help my opponent, and I want to know how to avoid this. I think I lost my sense of foresight when it comes to reading the board.

As for the latter, I often get notes that I could have checkmated my opponent in two moves, but instead it took my six moves to do it. 

Any advice for avoiding these mistakes?

Discovered attack needs preparation. So when you evaluate a position before finding moves, if you focus on the possible threats that your opponent can use, you can avoid it. Be careful when your opponent's bishop's diagonal is blocked with his piece. (also same for rook's file, and queen's diagonal and file)

@1

"falling for discovered attacks" ++ Pay more attention to those then, and from both sides.
If you fall victim to it, then you probably also miss cases where you could win with it.

"checkmating the opponent in inefficient ways"
++ Checkmate is checkmate, there is no bonus for doing it faster or more efficiently.

"I see what looks like a good move"
++ 'When you see a good move, look for a better one' - Lasker

"I want to know how to avoid this"
++ Blunder check before you move. 'Sit on your hands' - Tarrasch

"I could have checkmated my opponent in two moves, but instead it took my six moves"
++ Does not matter. Sometimes it is better to take the longer, but safer way.

According to the past history of your account, you are a typical beginner, you make a lot of blunders. Though, you are higher rated than what most people start at. Good job for that!

I have no idea what your basing what you wrote on, but it's not based on your past games. Maybe you played otb recently and fell for those traps?? Well, just because you played a few games and fell for a discovered mate in two of them that doesn't mean you are weak against that specific tactic. A game is a game. 3 games is nothing in retrospec. You need to play lots and lots of games, and I'm pretty sure most of those games won't be lost (your losses not wins) due to discovered attacks.

About missing mate in 2's... It's common for beginners to miss mate and two and turn it into a mate in 6 or 8. It comes with the territory. It's not something special to you, that's just what beginners do.

Given all of that, I would say the best thing to do would be to do what everyone else does, which is, quite surprisingly, play chess, and analyse your losses, once by yourself, and once with a stronger player, or coach. Also do tactics, and go over annotated master games. That's pretty much the basics of a good study regimine. You will need a theory book, and an endgame book. I don't recommend books so your on your own with that.

Let me reiterate this. I'm not calling you out. I'm not saying your stupid. I'm just saying, you are just like everybody else, you need to improve, by playing, and analyzing your own games. This is how you improve. There isn't anything special about it. You could have googled this and probably would have got the same response, but people like to write this stuff on the forums, questions that have been asked over and over again. I'm sorry if I am coming off as arrogant. I'm just speaking my mind. Anyway, I hope this helps. Good luck!

Regularly practice tactical puzzles, specifically those involving discovered attacks. This sharpens your ability to recognize and anticipate such tactics during games.

Never heard of something like ChessMood, I'll be sure to try it out

I don't really know what to recommend for older people but I highly recommend tring to get better at board vision most 800 have this issue "ill move my knight " then hang it to a bishop so like you said tactical sense important and you can only gain that from learning from your games (look at how and why you do bad not just what stockfish tells you analyze on your own ) and puzzles are always good

At your level just focus on getting better at tactics ,endgames (tbh the most important thing to reach 2000+ ) and being able to reach a good middle game ,tactics,mental resilience ,consistency is important so even if your stuck (taking a break can help) just playing games is useful ,learn how to do positional play ,watching YouTube videos can be good for that ,know when to break the good "habits" of chess and when to follow them ,openings but not really needed till 2000+ I only know one mainline of every most openings so understanding (and memorizing a bit ) can help you understand how to play in openings

Also don't resign always try to win your games cause your opponents will almost always blunder back like hikaru can beat 2500s down a queen for piece you would be able to pull some tricks off down a queen or a piece yourself

Do pretty much that if you think your tactical sense is an issue /noticing the tactics

Improving Your Chess - Resources for Beginners and Beyond.....

https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond