How to Practice
Play more 4Head
Setup
Setup
If you're ever in a situation where there is no solution, you likely made a mistake during the setup. Watch your own replays back to see what mistakes you made so that you know what you need to work on. Watching good players is a good way to learn setups. I'd recommend watching Nilgiri's replays to learn setups. You can also ask people what they would have setup with the pieces you had.
Solution
Solution
Put every PC you miss into a PC finder. Watching good players is a good way to learn solutions. Asking other people to find solutions is good because they could offer solutions you never even thought about, or an easy solution you missed. You can also make a Jstris map to practice solutions for a specific setup.