Like any recipe it all starts with good ingredients:
* Sifted sand that has a little bit of silt or clay in it
* Water (fresh or salt, doesn't matter for the sculpture but keep in mind it will make your metal tools and shovel rust)
* Buckets, shovels, forms, c-clamps and sculpting tools (trowels, palet knifes, horse brushes, forks, spoons, straws etc.
Often you have an idea what you are going to make. Based on the design you determine your form work and the sizes of the forms. Forms can be as small as a bucket with the bottom cut out, to trash cans without a bottom to plastic or plywood sheets clamped, strapped or nailed together to create larger sculptures.
Fill the forms with layers of about 6 to 8 inches of sand and thoroughly mix it with water. Compress the sand by pressing it down with your feet. Continue this process of layers until you reach a little more than the desired height of your sculpture.
Take a break, let the water drain.
Take the top form of and inspect the sand. Is it firm? Is it no longer jiggly? Determine if it safe to take the next form off if you have stacked several on top of each other.
Start drawing some lines on the block to determine where certain elements should go. Start taking away sand around it. Do not remove the sand where you would like the sculpture to be. It is a switch in your brain that you have to flip to take away around it and not take away at the design itself.
Sand is pretty forgiving and if you do end up taking too much off have a bucket ready with sand and water mixed to add some sand back on.
Keep gravity in mind in your design. It can help you but it will fight you if you're not careful.
Always start your sculpting on the top and work your way down.
Use big tools for big shapes and slowly down size your tools the more detail you would like to add to it.
Take a picture and start thinking about the next sculpture you would like to make.