Wall walking tips?

[ChrisM]

I've been watching a lot of movies via this site on how to get to special spots via wall walking. What I don't get is that whoever is doing it makes wall walking look like a piece of cake. What I am looking for are tips on how to wall walk so I can help find neat spots to get to.

Are only certain types of textures(general terrain) able to be wall walked on?
Does the distance you have to jump matter?
Does it have to be smooth or can you jump on curved surfaces?
Do you have to press anything specific while in the air or as you land?

I did a search for these but didn't get any solid feedback.

Thanks for any answers.