I'm as far from an expert as you can get, but I've done quite a bit of reading about snakebite treatment. It seems that traditional snake-bite kits are no longer recommended: The cut part seldom helps and often harms, and the suck part is not very effective in many cases.

Here's a snakebite checklist I'm working on to include in my day pack. Note: This is my first draft. I haven't yet run it by any experts to see if it makes sense. I am a know-nothing amateur, and you could die by following my checklist. Just because I read it in six different places doesn't make it true.

Snakebite checklist

Don't panic. Snakebites seldom kill. Panic often does.
Your goal: Get the victim safely to a hospital that has antivenin.

Get away from the snake
Be calm. Keep the victim calm.
Note the time.
Call 911. Continue with this checklist whether or not you were able to contact 911.
Keep the bitten limb still.
Have the victim lie down with the affected limb lower than the heart
If practical, splint the limb
Treat for shock and preserve body heat
Remove rings, bracelets, boots or other restricting items from the bitten extremity.
Wash bite with soap and water if available.
If help is not on the way (you were unable to contact 911):
Sit calmly for 20-30 minutes to let the venom localize at the site, then procede calmly to the nearest source of help (a place where the cellphone will work, or a place where there are people, or where the car is parked).
While waiting and moving, if you are a long distance from help, consider signalling periodically to see if anyone who can help is nearby (see signaling checklist).
If driving to help, drive calmly and safely. Snakebite is more survivable than a traffic accident. When you get cell phone coverage, pull over and call 911.

Do not cut the wound
Do not apply a tourniquet
Do not suck venom by mouth
Do not apply cold or ice packs