What should a beginner focus on to improve his level? I've learnt chess only about 1 month ago. Of course, my first game was terrible. But with reading some tips I've proceeded a little. Learning basics of few openings (like Spanish, Vienna and Urusov) increased my level and so did learning a bit about tactics (I can do a fork or a pin when possible) but now I don't know what to do? 

Should I read books on opening Theory? Or on endgame? I don't know how to make a plan. Sometimes in the mid-game, I don't see a good move. There is no great attack against me and also I did not make an attack but I'm not sure how to launch one so sometimes I tend to do a random move or just proceed to get my peaces more connected and controlling more place but I feel lost. So what would be your advice?

Is it better to focus on tactics and so? (Which resources do you recommend? text? app? etc ) or the ability to make a plan? (resource?)

Thank you in advance
A bit of everything, really.



Observe

Subscribe to a few youtube channels, turn up to tournaments, do something where you can analyse players who are better than you and try to understand their moves. This will give you a general idea of how to play, but won't teach you much compared to just playing.

Openings

Try to learn some basic opening ideas and maybe even a few more lines. Learning specific openings is only useful when you play exactly those openings, so you could either learn every opening in theory, or learn the main ones and a few opening techniques which would work across many openings.

"Opening ideas" Includes things such as piece development and centre control, but also subtle things too:


  Learning the ideas behind openings means, rather than memorizing long theoretical variations it is important to know where to put your pieces and make a pawn formation and build a long term plan accordingly. Every opening is unique and has its own ideas, some openings require fast and aggressive ideas and motifs and some openings it is important to play slow and just maneuver your pieces to a good square.


This post by GM arunabi is a great material that looks into opening ideas.

Middlegame

Try to  brush up on things like positional play and trading. Learn a little about pawn structure and when to castle. You can set up your board to the end of an opening line and play against someone else or a computer to acheive this. Watching GM games on YouTube helped me a lot, since you begin understand how trading works and how the value of pieces can change. @Bad_Bishop wrote an amazing answer to my question about trading minor pieces which you should read.

Endgame

Practise a few endgames and start to calculate best moves in difficult endgames. Playing an endgame as the losing side and trying to draw may even be more beneficial to your learning. You can easily do this by playing against a computer and starting in a losing position. You can take these positions from famous games, your own games, or random games from a chess database where there was a clear winner, and starting ten or so moves from the end.

Review

If you have records of your games, go and find out where your mistakes were. After every new game you play, run back through it and find where the turning points of the game were. Try to pinpoint mvoes which caused the play to shift. Identify the tactics used and go and learn those, so you can spot them next time.



The most important part is to keep playing games and reviewing them to find your own weaknesses. Once you find them, stamp them out and repeat.