Given the basic Third Edition rules I would have some of the following
comments:

* Get all your special (non-lineman) players first. I generally like this
  for any team. Emphasize acquiring both Storm Vermin ASAP to get them
  going. This is vital depending upon how your league uses Rat Ogres.

* Skaven Lineman have enough move to make them really useful in a variety
  of situations and I recommend building a few types. I liked to get a
  pair with Block and Strip Ball (Dauntless with this is even better).
  I would send these two running into the backfield after the ball every
  turn on defense without any regard for their health. They caused a lot
  of turnovers, and were not hard to re-build if they died. They are also
  very annoying to many coaches, which is always a plus in my book. You
  can very easily use a Skaven lineman as a safety, and only one is needed
  to cover the field.

* Once I had the ball I found that moving the Skaven around the opponents,
  and just placing them next to as many of the closest opponents to the
  ball, was good. They generally got in the way enough to allow a GR to
  run into the endzone.

* Everyone knows to build a few one-round scorers with your 4 GRs. I like
  to have the Block/Dless/DT GR or two to put to good use. I know a Skaven
  coach who would take these guys and throw the DT block no matter what
  the odds, whether or not this GR had Dauntless yet. That ended in a bad
  situation most of the time, so use some discretion.

* I never had to give Accurate to my Throwers because they always got AG+1
  from hanging around the GRs.

* Make the Skaven EAT the warpstone, not just play with it. You get more
  mutations that way, trust me.

* Skaven linemen are so much more useful than almost any other linemen
  because of that MA7. Anyone can make good SV, GRs, ROs, and Throwers,
  but good use of the lineman makes a good team great.
--
Aaron Thies