I'm writing a long elaborate guide on how to develop in chess for the first time. It's largely based on my experience of guiding two or three streamers on their way from 700 to 1400, or from 1100 to 1700. I'll also make this a standard reference for everyone asking this super frequent question.
Accept that you need patience and you can't climb the rating ladder in just a few days or weeks. Chess is a long-time commitment especially when you're absolutely new to it. Now I'll describe a typical pattern on how to develop skill. This is not to be understood as a fixed order, it's a continuous process. What makes all of these steps successful is regular practice. Play rated games in the pool with slow time controls, preferrably with increment. Do a bunch of puzzles every day (or at least every 2nd day :-)). Lichess also offers some basic training material in
lichess.org/practice. Your improvement will transfer from slow time controls to faster ones, not the other way round. I'd say don't blitz too much, and definitely keep your hands off bullet as long as you're lacking experience for fast play.
First step: Stop blundering pieces (that is, straight blunders must be less and less frequent). The very first thing for beginners is to not put pieces on unprotected squares where they can be captured directly. This is the part that will frustrate beginners the most. But your opponents are not better so often you'll also get the happy opportunity to snack a free piece of theirs.
Second step: Learn about basic mating patterns. Mating with a queen (don't stalemate!), two rooks (or rook+queen) and just a single rook. Also backrank and basic queen infiltrations (Ng4+Qh2, Bd6+Qh2, Bc6+Qg2, pawn f3/h3 + Qg2 etc).
Third step: Be aware of the typical value of pieces. The difference between rook and minor piece is considered 2 pawns on average, in fact rather tending to 1.5 pawns. Two minor pieces are most definitely stronger than a rook. A queen is better than rook+minor piece, and roughly equal to two rooks (convention says +1 for the rooks. but it highly depends on how safe the king of the rook party is). Minor pieces are roughly 3 pawns. But the less pieces remaining on the board, the more important the pawns. If there are no pawns left, you need at least a rook to win.
The value of pieces also comes together with basic protection rules. How often is a piece attacked by the opponent and how often is it protected? But also, what's the priority of pieces, and are they in each others way or not? For example, it makes no sense to:
a) protect a square with queen and king when it's attacked by two minor pieces.
b) attack a pawn with two pieces when it's protected by another pawn.
c) protect a piece with your queen and a rook/bishop standing behind when it's attacked by two lower-valued pieces. As the rook/bishop is standing behind the queen, it won't be the first to recapture and you'll definitely lose material.
Fourth step: Alongside the basic principles on what makes a piece hanging, get familiar with basic tactics. Pins, forks, skewers, discoveries, fake protection, attraction/distraction etc. Even at higher level, a ton of games is decided just from one of these basics.
Fifth step: Get into basic endgame theory. Endgames with a single pawn, remote and protected passed pawn, breakthroughs, winning with queen against 7th rank pawn (or knowing when it's drawn), rook + pawn vs rook, the wrong-squared bishop, knight vs border pawn etc.
They all complain to their coaches and master idols: "please help me in this or that opening" ... the endgame is where wins, losses and draws are decided!
Sixth step: Healthy opening. We're not talking about specific openings yet. Just about the golden rules, to claim the center, free your pieces, get all your pieces into play, castle and connect rooks, make all your pieces as effective as possible. But also watch out for tactics immediately, especially don't get scholar-mated or lose material early. Of course, one could object that opening hardly matters at beginner level because games are still blundered and reblundered at any time. But a good base to start is still absolutely recommendable, it allows for comfortable wins and avoids early disasters. If you have the need to get to know common openings, feel free to, but don't emphasize on it too much.
At this point you should have established a rapid rating of I guess at least 1500 and you should be happy with your play even when you have phases of stagnation. At this point it's up to you how much you're determined to keep improving and get into the advanced stages of positional play, weaknesses, imbalances, offensive and defensive patterns, initiative, endgame activity, an opening repertoire etc. Books, videos, streamers, OTB clubs are good sources for that. But first, I absolutely predict, you will need several months to complete the basic steps.
