I find that background is key! Complimentary colours make the snakes really stand out ie orange snake on a blue background, as you have already done. I have taken pictures with Lacey (purple snake) on a green background and they turned out lovely.
I frequently photograph my snakes on a black background but thats because its clean and universally friendly
The only editing softwear I have is photoshop, and that runs for about £800 (if you buy it). But its an amazing program and you can do so much more than edit photos in it.... Like the attachment of Edward I drew for example.
Also remember composition. ie balanced photography. If the snake is looking away or only their head has been slightly cropped I feel its a bad picture. If the face is not in focus, i also feel its a bad picture. I try to capture the snakes in an interesting position, either curled up or posing on some form of branch.
Lighting is also extremely important George. The more light the better. Although I use my flash more often than not as I rarely get a chance to take outdoor pictures
But your editing software can make all the difference to a "bad photo". I have found lots of ways to touch up photos. Anything from spots of too intense lighting to a fuzzy face.
