I have checked your profile and analyzed some of your chess games, let me summarize my analysis in three sections.

Let’s watch one of your recent chess game.
Opening Suggestion:
In one of your recent game you played Viena Game, which is ok and sound opening and its has theory to learn and there are many positions in vienna where you have to know everything before playing or you will be crushed in the opening.
So my suggestion is that you should play with Bishop’s Opening, this opening is very sharp and straight to the point which is to checkmate black’s king or get enough compensation such as space advantage or huge center.
In one of your game against Owen defense, you did not play according to opening theory. Playing against Owen Defense is easy for white and you can win in 15 moves. Check out famous trap in owen defense at Youtube.
Let’s watch one of your chess game with black pieces. Please Flip the board to blackside for a better view.
In above game, on move 4 when you played move Nf6, you missed the chance to equalize white’s advantage in one move, the best move was e5 move, quickly challenging the center and destroying the center followed by long castle.
With black pieces you are playing d5 against d4, which is by far strongest move. I would like to suggest that in Scandinavian defense, you should not play Nf6 move instead capture the pawn right away with Qxd5 and then move your queen to Qa5. This variation is easy to play and before playing this you must watch some traps of Qa5 on Youtube. Because in some variation black’s queen is trapped in the opening.
Middlegame Suggestion:
In the middlegame, you have only two plans and goals. One is how to create a weakness in your opponent’s camp and second is how to exploit it.
If you don’t know yet how to find weakness in your opponent’s camp, then this guide may help you.
Another guide for middlegame is, learn chess strategies and tactics.
In order to reach 1500 rating, you must master techniques for strategies and tactics. Here is article which might help you: https://chessrewards.com/chess-strategies-and-tactics/
Endgame Suggestions:
In the endgame, you often neglected the most important topic, which is to create a passed pawn and playing with your active rook.
For improving endgame, you must learn Pawn and King endgame and Rook and Pawn endgame. LearnĀ some famous rook positions like lucena position.
Conclusion
In the opening, learn Bishop Opening, and Scandinavian Defense with Qa5 Variation. In the middlegame learn how to create weakness. In the endgame, learn rook endgame and king and pawn endgame. If you apply my suggestion and work on my advice you will get 1500 rating in two months.
If you still have any question, feel free to ask below in comments.