The best way to improve is to play games with people as good as you or a bit better. Before the game starts, practice a few pots, squops and bring-ins on the mat you are about to use. If you really don't know what to do, do what you think you can get. Play according to your capabilities. Play reasonably quickly.
Fast games are more interesting and more fun.
Don't get annoyed by a miscalculation or a missed shot, as it only increase your chances of doing it again. Discuss the game with your opponent afterwards. If your opponent played any shots you've not seen before, ask how they're done. The National Singles. If any tiddlywinks tournament can claim to matter, it is this one.