Ok let’s have a stab at this in no particular order:
Stand on the pedals
Look up to where you want to go
Brake in straight lines
Lean the bike not the body
Speed will carry you through
surely they aren’t skills, but guidelines or mantras….
i’d go with…
1. bunny hop
2. cornering
3. trackstand (helps a lot with bike handling, IMO)
4. riding drops/step downs
5. pedalling off/getting off the bike on a steep incline (am often amazed at how some people have now idea about this. people trying to scoot along to get enough momentum so that they can start pedalling or trying to step off the bike from the side – both manouvers resulting in a comedy (but sometimes painful) fall).