What you want to do is stop the venom from traveling from the site of the bite, into the lymphatic system and then into the bloodstream.

DO NOT suck, cut, wash or otherwise investigate the wound. EDIT: Do not try to catch or kill the snake, identifying the kind of snake is NOT worth the risk of a second bite and the delay in getting to your other priorities.

Priority 1- get away from the snake.

Priority 2- get help. Get someone nearby to call an ambulance.

Priority 3- stay still. Moving your muscles is what helps pump the fluid through your lymphatic system and to the lymph nodes, where it can enter the bloodstream quickest. Ideally, keep the bite below your heart, but immobilization is the most important thing.

Priority 4. If there is someone with you, get them to apply a pressure dressing to tightly compress the whole limb. This can greatly slow the flow of lymph and buy you hours.