You can do just about anything your heart desires in a tank, just ask yourself one question, how will this change the quality of my water? If you look at my profile you can see my pictures of my two tanks one I finished today.
One has a lighter sand, the other a darker sand. I use drift wood that has been (ironically ) sand blasted. The lighter sand I use is actually sand blasting sand (not glass beads or black diamond cut) I got mine from Tractor Depot when they have it. It's a whiter sand and easily washable. I use slate from a local roofing company drill holes in it, and attach the drift wood with screws, I just cover the slate with sand. The darker tank is just mortar sand used for mixing concrete I like the texture of it better than the play sand and it has small pebbles in it. I got that at Lowes just down from the play sand. Rinse this stuff out.
I also use a multitude of easy growing plants. Some floating some rooted. I like to keep my tanks somewhat natural looking. But it's up to you, how you want to design and place your tank items. Plant cover fish love it, and so do fry. If you don't have live plants fake ones are good too, and yes they look different in the water than they do in the package.
My first setup I used stone from our local creek, I used mainly the smaller stone, and no I didn't wash it, as the stone itself will already contain some of the basic bacteria needed to start or cycle a tank, just watch out for lime stone, it will change your water levels. ( I don't recommend this process if you are in a hurry to get nice fish in there, it takes some time to get the levels to settle and the tank to cycle)
I've only started myself in the aquatic hobby, not only is it fun, but it's very relaxing. Just remember we all loose some fish, but once you get the simple stuff down, you just move on to more adventurous tanks. Hope this helps you out some, I'm by no means an expert, but from what I've learned from other's on the forums, and my good friend Mac, I've only lost one adult fish so far.