See the FDA's page:
http://www.fda.gov/Fdac/features/995_snakes.html

What not to do, according to the page:
No incisions in the wound
No tourniquets
No ice or other cooling of the wound.

The page has information on what to do till quick help arrives and what to do if you can't get help for hours.

One expert says,
Quote:
"In the past five or 10 years, there's been a backing off in first aid from really invasive things like making incisions," says Arizona physician David Hardy, M.D., who studies snakebite epidemiology. "This is because we now know these things can do harm and we don't know if they really change the outcome."

So you may be seeing out of date advice regarding tourniquets (now uniformly rejected in all sorts of wounds), incisions, and sucking.