Sorry i'm also a little unsure what your meaning. Have you played with other warbanrd and know the rules? or do you mean playnig a few games to learn skaven?
For a typical skaven list try going for a mix of about 12 models, and buy some of the nicer gea rlike warplock pistols, fighting claws etc. try them out in a few games and then decide what works. Once you know your style (Do you like splitting up into smaller hit and run groups, or prehaps mass assaulting or over whelming the enemy) then pick the items which play to yoru strengths.
Example sof this could be loading up on heroes and making a small well geared band about 12, or taking the rat ogre and attempting a small elite warband, or even taking 18 cheaply armed guys with slings or clubs and daggers to overwhelm with mass attacks.
Just remember your guys have a terrible leadership so you need to try to stick about and learn how fragile they are compared to the other warbands you'll be playing.