MTG Casual snake deck, U/G. Advice?

It looks good so far, but I must agree with my peers. Champions, Betrayers, and Saviors of Kamigawa were the best snake series in the game thus far. Go there and grab a few singles from that set. The packs cost too much. I play a snake deck myself, and here is what I would toss in:

Sakura Tribe Springcaller - Mana production that doesn't cause mana burn (not that it would anyway)

Seshiro the Anointed - +2/+2 for all snakes and you get to draw whenever snakes do damage

Sachi, daughter of Seshiro - +0/+1 for all snakes and all shamans become able to generate 2 green mana

Sosuke, son of seshiro - +1/+0 for all snakes and all snakes get deathtouch basically

Konda's banner - put it on any of the Seshiro family and all your snakes get +2/+2.

You might also think about using Orochi hatchery, but it'd have to be late in the game.

I would also swap out snakeform with diminish. Diminish costs less and does essentially the same thing. Take out the river boa for sure. But other than that, it looks ok. Let me know how it looks once you get all the cards you want in there. Good luck!

Mtg Snake Deck

Go with the suggestions here, add some cards from Kamigawa block. Mystic Snake (Time Spiral) and Ohran Viper (Coldsnap) are interesting additions. Coat of Arms is also nice. Not a lot of Snake cards from Lorwyn to Eldrazi, aside from what you've listed.

The most snakes printed in the game were in the Kamigawa block (hundreds there) and there were some very good ones. I suggest buying packs from those sets to make a snake deck.