I recommend you take out
poultice sliver, it's pretty bad (plus I have
crypt sliver in my deck, which is way better). Also, put in either
boros charm or
lightning bolt (even
lightning helix if you really want to).
Clifftop retreat is a good special land, but I like the one you have too. You have quite a lot of high costs, but you also have a lot of low costs too, and plus I have
gemhide sliver which helps with mana ramp, so you might want to take out a few lands because of my gemhide, but you don't have to. If you want a 1 drop creature,
plated sliver and
sidewinder sliver are pretty good.
Homing sliver is really good if you want more red, you should replace poultice with it since its the same mana cost and has the same power and toughness. Finally, replace
belligerent sliver with
two headed sliver since it affects all slivers (not just ones you control) and costs 1 less mana. Its a shame though, since
belligerent sliver has awesome artwork. Otherwise it's a pretty good deck. But there are too many slivers. 7.8/10 -ign