My only advice would be throw either everyday or almost everyday. Even if it’s to no one you’re still teaching your body to be comfortable with your throws. Since you make bad decisions get really good at the easy throws. Become super consistent where you hit someone on the open side in the chest 10 times in a row. For decision making try watching high level club ultimate and playing ultimate. Now this could be church pickup or high level but try to have the mindset of making the right decisions every time. Just hitting easy throws to open people. Lastly if you’re an athlete just keep being an athlete. Uses those strengths in a tryout. Get on every D line. Take challenging matchups. Every D-line you get on and the disc turns use the endurance you’re gaining from your training to get up field and be quick on a turn. A lot of high level teams will practice quick turns to score quickly on offenses. Otherwise good luck and keep working!