I don't know how much filming experience you have in general - that's kind of critical because it affects what advice matters to you - but most importantly just have fun. Film what looks good. Be creative. Try and imagine what you want your edit to look like before you shoot it and work towards that as you film.
i feel like montages are getting sort of played out in skateboarding, they don't seem to be as creative as a whole (obvious exceptions1 see nikes video and rise and shine) like the last guy said try to do new stuff.