I remember reading the following simple rule in a book about playing slide guitar: "Rule 1 of playing slide guitar - there aren't any rules".
I use an Open G tuning mainly and have been picking up tips from a banjo player - a five string banjo also has an open G tuning. So, I've learnt some chords that take a bit of mucking around given the slide on my little finger and that the banjo chords only cover four strings.
Otherwise, experiment with other musos who are happy for you to experiment and hit the occasional bung note.