If you're looking for some cowboy celebrity stunt of grabbing snakes out of trees and so on, you're in the wrong place.

This guide works well in conjunction with the two other snake-related Instructables:
Snake (or Hook) Stick - which can be viewed here.
Snake Tube - which can be viewed here.

There are a few things to remember when dealing with snakes:

1) Snakes are not toys. Only catch a snake for qualified research purposes, or if you absolutely have to. Remember, it's stressful for the animal to be captured.
2) Start small. Don't try catching a 2-metre cobra on your first day out, you'll come off second best. Start with practising the wrist movements and techniques on a rubber snake or a thick piece of rope. The rope works well because if it's as thick as a snake, it reacts a little bit like one in terms of flexibility. Once you're confident in that, move onto a harmless species, and practise on it. Preferably use a specimen bred in captivity as opposed to a wild snake. Captive-breds are more used to human interaction and you'll therefore cause it less stress.
3) SNAKES ARE NOT TOYS.
4) Know your species. Pretty basic, but important. Know what snakes you're likely to encounter around your area, some are more aggressive than others etc etc etc.
5) SNAKES ARE NOT TOYS.
6) Focus on the snake. Don't answer your phone with a snake in the hand, again, you'll come off second best.

And this is probably the most important thing to remember when dealing with venomous snakes:
COMPLACENCY KILLS. Just because you've caught a hundred snakes successfully doesn't change anything.

Finally, this is obviously just a guide - I recommend attending a handling course or something similar where a professional can teach you face to face about dealing with snakes.

Step 1: Pinning

Snake sticks have a flat head which can be effectively used to pin down a snake before it manages to slither into cluttered areas. This feature is helpful if you're catching one in a house or somewhere where the catching process can be complicated be objects.

It also allows you to subdue the snake while people vacate the area. Having too many people around you will restrict your movement and adds a serious danger factor to the equation, always have at least a few metres around you where nobody is allowed to stand.

Never squash a snake down like this, use only enough force to keep it from slithering away.

*The snake used in these photos is not real.

Step 2: Lifting (Hook Stick Only) Step 1

The one way to catch a snake is to lift it up in the middle.

Start by moving your hook stick towards the snake about a third of the way from the head. (Almost all methods of catching snakes will involve dividing the snake up into thirds)

Keep the hook stick fairly flat on the ground and move it in underneath the snake.

Step 3: Lifting (Hook Stick Only) Step 2

At this point the snake will usually try to move away from you.

Turn the hook stick so that the hook points up.

Lift the snake off the ground.

If your timing is correct, you'll lift at the same time that the hook is nicely in the middle of the snake (Remember you started a third of the way from the head).

If you try hooking the snake up from the middle and not from slightly to the front, more likely it'll slither straight off the hook when you lift it up.

It's no train smash if you don't get it right the first time, just try again.

Step 4: Tailing a Snake (Step 1)

Tailing involves actually gripping the snake's tail while lifting it up.
This is a handy technique to use for two reasons:
1) You can catch much longer snakes this way
2) You'll have much more control over it

Tailing can be dangerous, and do not try tailing any adder/viper species!!

The first step is getting the snake's tail in your left hand. The reason for this is that all your left hand really needs to do is hold on or let go, your right hand (the controlling hand) has to constantly do fine adjustments to the hook etc. This is obviously the other way around if you're left handed.

Hook the snake at a third of the way from the back and lift the tail up to your hand. If it's a long snake, hook it at a third of the way from the front, then let it slither through the hook while you lift the hook back and upwards, timing it right so that you can get hold of the tip of the tail (just behind the cloaca) in your left hand.

Immediately readjust your hook and hook up the snake a third of the way from the head. The photo shows this step of once the tail is in your hand.

Keep a safe distance at all times.

Step 5: Tailing a Snake (Step 2)

Now the beauty in tailing is revealed.

By keeping the tail elevated as you can see in the photo, you make it difficult for the snake to move backwards. This is the secret of tailing, keeping the tail higher than the head.

Beware of a few things here though:

+ Boomslang, cobras and such species can zip up the shaft of the stick if the get a hold, stay alert at all times.
+ Adders should never be tailed as they are much too powerful when striking (I'm not sure about other species like rattlers, but with Puff Adders tailing is a death wish.) Adders and vipers have enough force in a strike to actually lift themselves clean out of the hook - Bad news.
+ Avoid letting a snake (especially an elapid) wrap it's tail around your wrist, they have excellent muscles and can lift themselves off the hook if they manage to get a good tail grip.
+ Also, because the tail is higher than the head and closer to you, if the snake gets his head out of the hook it'll come swinging right towards you.
In short, be ready to down tools (and snake) at any moment.

Step 6: Leading the Snake

Once you have the snake tailed, you can proceed to bag it.

Very simple,
Angle the snake so that the head faces the entrance to the tube,
Lay the snakes head on the ground (don't remove the hook yet)
Once the snake's head and first third are in the tube, remove the hook and place it against the entrance just above the snake's back to prevent it from doubling back and exiting the tube again without warning.

Once the snake is inside the bag, lift the tube up and seal the entrance. Remove the tube, seal the bag and hey presto, you've caught a snake.