I would give you the same advice I give almost all of my students. Beginners make the mistake that they think they have to learn things. They want to learn new openings, they want to learn endgames, etc. But if you think about it, this theoretical information might affect about 1/20 to 1/50 games, which essentially has a completely negligible impact on rating. As long as you aren't consistently losing as a result of one of those things, it is unnecessary.
Anyway, trying to learn new information is just entirely the wrong approach. Most beginners (say 1200 like you are) already have all of the knowledge they need to become a higher rating (say 1500-1700). They don't need to learn new openings, they don't need to learn new endgames. What needs to happen is they just need to at all costs avoid making mistakes. That is the single biggest differentiator in the rating range of about 1200-1700. If a 1200 player woke up one day and just stopped making simple mistakes (not hanging pieces outright/ not hanging anything to simple 1 or 2 move tactics) then they would almost immediately be beating players way out of their rating class.
The reason for this is players under about 1800 don't really know how to wait, do nothing, and not self destruct. My experience is if you give any player under 1800 long enough and just play ok moves, eventually they will hand you a game losing blunder.
So knowing this there are two pieces of advice I would give you.
1. Take an excessively defensive view of the game. You can't control whether your opponents make mistakes. You can however control if you make a mistake. If you miss an opportunity to win a piece, while regrettable, you are still entirely in the game! If you blunder a piece for no reason on the other hand, the game is over. Try to think of what your opponent wants to do, try to examine your position for weaknesses (at any point in the game you should be able to name every single undefended piece on the board quite quickly, especially (but not only) your own.
I remember watching a tournament about a year ago and the commentator said "One of the toughest things about John [Bartholomew] is that he doesn't beat himself, you have to make him lose" BE that player! Don't make it easy for your opponent to win, don't hand them wins they didn't earn.
2. Try to put yourself in a position where you are ready to take advantage of other people's mistakes. This does entail training in tactics, but it also requires knowing why and how the tactics work. You don't want to be a lord of puzzles and tactics off the board and miss all of them on the board. The single biggest indicator that the position might have tactics is loose pieces and tension (captures are possible). Try to develop a very good sense of when you need to be looking for a tactic by focusing on those two things.
3. A few resources to help you (in order of importance imo):
www.youtube.com/watch?v=8kdjSqNcViw&list=PLl9uuRYQ-6MBwqkmwT42l1fI7Z0bYuwwO
www.youtube.com/watch?v=fzGKPxJ5NYI
www.youtube.com/watch?v=0g9SlVdv1PY&list=PLQsLDm9Rq9bEvlHwbsWlt5sta3M2t0aGe
www.youtube.com/watch?v=U2huVf1l4UE&list=PLl9uuRYQ-6MCBnhtCk_bTZsD8GxeWP6BV (the first 6)
www.youtube.com/watch?v=L2CK5FKC5Zs&list=PLUjxDD7HNNThPhpIiBIb_8weNic1DEbJe (the first 8)
www.youtube.com/watch?v=Ytkf3qZTj74&list=PLT1F2nOxLHOcmi_qi1BbY6axf5xLFEcit (any of them, there's alot lol)
Obviously that is a lot of content, you can't really watch all of it in a month and it isn't really mandatory. Watch the videos you enjoy watching, it shouldn't feel like a chore.
Anyway, trying to learn new information is just entirely the wrong approach. Most beginners (say 1200 like you are) already have all of the knowledge they need to become a higher rating (say 1500-1700). They don't need to learn new openings, they don't need to learn new endgames. What needs to happen is they just need to at all costs avoid making mistakes. That is the single biggest differentiator in the rating range of about 1200-1700. If a 1200 player woke up one day and just stopped making simple mistakes (not hanging pieces outright/ not hanging anything to simple 1 or 2 move tactics) then they would almost immediately be beating players way out of their rating class.
The reason for this is players under about 1800 don't really know how to wait, do nothing, and not self destruct. My experience is if you give any player under 1800 long enough and just play ok moves, eventually they will hand you a game losing blunder.
So knowing this there are two pieces of advice I would give you.
1. Take an excessively defensive view of the game. You can't control whether your opponents make mistakes. You can however control if you make a mistake. If you miss an opportunity to win a piece, while regrettable, you are still entirely in the game! If you blunder a piece for no reason on the other hand, the game is over. Try to think of what your opponent wants to do, try to examine your position for weaknesses (at any point in the game you should be able to name every single undefended piece on the board quite quickly, especially (but not only) your own.
I remember watching a tournament about a year ago and the commentator said "One of the toughest things about John [Bartholomew] is that he doesn't beat himself, you have to make him lose" BE that player! Don't make it easy for your opponent to win, don't hand them wins they didn't earn.
2. Try to put yourself in a position where you are ready to take advantage of other people's mistakes. This does entail training in tactics, but it also requires knowing why and how the tactics work. You don't want to be a lord of puzzles and tactics off the board and miss all of them on the board. The single biggest indicator that the position might have tactics is loose pieces and tension (captures are possible). Try to develop a very good sense of when you need to be looking for a tactic by focusing on those two things.
3. A few resources to help you (in order of importance imo):
www.youtube.com/watch?v=8kdjSqNcViw&list=PLl9uuRYQ-6MBwqkmwT42l1fI7Z0bYuwwO
www.youtube.com/watch?v=fzGKPxJ5NYI
www.youtube.com/watch?v=0g9SlVdv1PY&list=PLQsLDm9Rq9bEvlHwbsWlt5sta3M2t0aGe
www.youtube.com/watch?v=U2huVf1l4UE&list=PLl9uuRYQ-6MCBnhtCk_bTZsD8GxeWP6BV (the first 6)
www.youtube.com/watch?v=L2CK5FKC5Zs&list=PLUjxDD7HNNThPhpIiBIb_8weNic1DEbJe (the first 8)
www.youtube.com/watch?v=Ytkf3qZTj74&list=PLT1F2nOxLHOcmi_qi1BbY6axf5xLFEcit (any of them, there's alot lol)
Obviously that is a lot of content, you can't really watch all of it in a month and it isn't really mandatory. Watch the videos you enjoy watching, it shouldn't feel like a chore.