Stuck at 400 elo after playing chess for a year

Hey. I've been playing chess for almost a year and I'm still stuck at 300-400 elo. How can I break through it and reach 500-600 elo?

Looking at your last dozen losses - you tend to resign or abandon in middle games that are relatively even and sometimes slightly in your favor. So, stop giving up when your opponent makes a serious threat and instead look for ways to counter attack, defend, etc. Don't be afraid to trade queens, especially when you're up a piece - and, at your level, keep playing even when you lose your queen - you'll never get better at coordinating your pieces if you only teach yourself to rely on your queen. Do custom puzzles to get better at spotting potential knight forks so you can avoid them. In fact, start doing puzzles regularly to become more familiar with general tactics - your openings seem pretty sound, but as you enter the middle game it seems like you're unsure of how to progress - learning to spot tactics will help a lot.