https://ultiworld.com/2020/03/24/tuesday-tips-throwing-alone/
If you don't wanna go too far and have some discs, I've been doing this for awhile (before social isolation was the hip new thing), and it really does help. If you're starting out, see if you can get the disc to come out of your hand consistently flat, without a wobble. Try to hit a lacrosse goal (or some imaginary area about the size of a person) consistently from 10 yards.
After that, pace off 15-20 yards and try to hit the target with inside-out, outside-in, and flat throws consistently.
For the big throwers, try to throw hucks and group them as close as you can to get your consistency down (and also get them to fly in the path you intended).
In all cases, it's a low pressure situation. There's no 10-second limit on your throw, so you can think about the throws and tinker with your form, release points, your pivot, and so on.
See you out there soon.
Chuck