Your thought process for now needs to be focused on ensuring you get you pieces out safely and centralized, look for tactics to win material and avoid losing material by ensuring your pieces are adequately defended and calculating against threats. As you progress other factors will need to be considered but for now it’s all about making safe active moves and capitalizing on your opponents blunders, and blunder they will.
My study advice is;
Play Daily chess. Each position do the above as best you can. Don’t rush any moves.
Solve puzzles every day. At least spend 10-15 minutes a day solving puzzles. Never guess answers, calculate until you know you have it solved. If you get any wrong review it until you understand what you missed and why you likely missed it (unfamiliar pattern, miscalculation, ect).
ChessAble has some great free courses on tactics, endgames, and short opening lines. I recommend looking into those.
just wondering what you guys have done to expand your skills. i have felt stuck at sub 400 for a while and im trying to improve