Presume your going to be applying mulitfinish onto plasterboards if thats the case you want to get yourself a roller & apply a pva to the boards a mix of 3parts 1 to 1 part pva. Wait until its tacky then you can apply the plaster, this stops the gypsum in the board sucking the moisture out your plaster when your applying it.

Keep your tools clean & use a good float with not scratchs in it if you want a damn good finish, make sure when you mix your plaster you get it to a good consistency like chocolate mouse

When your putting the plaster on the wall load up the float with plenty of plaster then start at the top & come down halfway dont close up the float too soon or you'll end up with bubbles in the plaster & too much in 1 area. Only do a small area at a time then work from the bottom & not very bottom about 2inchs from bottom should do then do same as you did the top but when you get halfway dont keep dragging up turn the trowl & swipe across.

Once you got a small area done start floating it from the side to level it out, once your done them 3 steps until all your plasters on the wall. Leave it for about 5-10 minutes using the time to clean up your tools.

Don't worry it the 1st coat is a bit crap the 2nd coat will hide the imperfections. Get a bottle with a trigger head & spray the wall with clean water not too much then using a clean damp flaot just wet trowl the wall this is called "polishing" DO NOT WIPE OFF ANY PLASTER YOU PICK UP this can be used to fill any little bits you missed, work downwards. After that use a dry float with no water.

Get your 2nd cat on doing the same thing again.

Also get yourself a soft 1inch paintbrush & using the trigget bottle wet it & plaster & you can blend in the corners with it known as the "magic wand"

lol think i covered most of it. hth