First things are opening which guide you through both the opening and the midgame because your plan from the opening goes in connection to the midgame. Next is the midgame where the game is mostly decided at where maybe endgames take 2nd place in where most games are decided at. In the midgame you need to learn about these things in order of most important to least important(this is my opinion on the order so share ideas if you think this could change or things I could add). Stop blundering pieces/tactics, positional play, attacking play, and defensive play. Stop making mistakes is the 1st one and a way to reliably stop making these mistakes are removing/trading off anything that can punish you for a mistake and 2nd is positional play with correct positioning of the pieces, choking your opponent of space, weak squares and controlling them, and putting pieces to the most forward squares available and 3rd is attacking with, pawn storms, bring the pieces into the attack, and sacrifices and 4th defensive play is where you trade off the attackers, counter attack, and keep a steady pawn structure around the king. Endgames are the finals where some games are decided and the games you should mostly study are Rook endgames and pawn endgames, but you should also spend some time into other endgames. Here are some things to get you started or ready with endgames. With rook endgames protect your 2nd rank because if the opposing rook infiltrates there then most of your pawns are going to get targeted there and you may lose some of them and check to see if you can infiltrate on the 2nd rank from your opponent’s perspective to attack a bunch of pawn and remember to take control of the open file and always remember to bring the king to pawn weaknesses and practice the Lucena and Philidor’s position in rook endgames. For pawn endgames you should bring your king to the weak pawns of your opponent’s perspective meaning doubled, tripled, isolated pawns are targets. For Queen endgames you should protect your king while at the same time bring it to an active position and if you are winning the queen endgames watch out for perpetual check from the opposing queen. In a N vs B scenario and you are in the side with the knight you should put all your pawns on the opposite color of the bishop and don’t put your pawns on the color of the bishop and if you can’t do that then protect them or if you can sacrifice them to promote and if you are in the side with the bishop try to block the opposing knight with pawns or bishop and limit it’s movement and once again the king is important here. In a different colored bishops against each other endgame you should put your pawns on the opposite color of the opposing bishop and the king will be used here again. In an endgame with same colored bishops the thing to do here I think you can guess, putting your pawns on the opposite color of the opposing bishop , but now it is more drawish and then what happens next is if either one of you will lose on time or agree on a draw and remember the king. If you need more detail on the things I talked about check the youtube channels “Remote chess academy” and “chess vibes” on to youtube. The last tips I will give you is about time managementment and chess psychology. First with time management if you have 2 moves that you want to do equally then just choose one or use the most forward move out pf the 2 or 3 or 4. Next with chess psychology don’t overestimate or underestimate your opponent because if you do then you will underperform, so my recommendation is to activate a mode in settings that makes you not see the ratings of your opponent so this will not happen and don’t be too exited or else you won’t focus on the game and this also goes for if you are super tired or sleepy. If you lose 1 or 2 games(I recommend only 1) on one day then it is better to rest and save energy for tomorrow. This is for the elos 100-2000, but if you are above this rating, but still want to improve, you can use this.