My suggestions:
Have a DSB- As previously stated, you need the critters. The critters that live in the sand will do alot of the work for you. Not to mention, they'll help feed your tank. (Yea, DewMan- 3-4 inches is absolutely acceptable.) Read this for more information on DSB's:
http://www.rshimek.com/reef/sediment.htm
Buy uncured liverock and keep the lights on- If you mail order liverock, no matter what you should consider it "uncured." Even if they say it's cured, there's no way for them to prevent dieoff when they ship it from their holding tanks, to you. Maybe the dieoff won't be as bad as when you buy uncured live rock, but you're going to have to cycle your tank anyways. I do also suggest turning the lights on in your tank with liverock in there. There's always the possibility of corals (no matter how small) living through the shipment. You never know- by not keeping the lights on, you might kill a really rare coral!
Buy also a clean up crew- Granted, the liverock will provide alot of critters for your DSB, the more the better! It's even better if you get "critters" from two seperate sources.. more diversity is the key to a healthy sand bed!
Stay away from Crabs, Shrimp, all that stuff- Yea, they eat algae, yea, they look cool. But when you've got no algae to eat (which there will come a time for you hopefully) they will gladly devour all your critters in the sand! I look at them as pests, and get rid of them as soon as I see them. You're better off starting right from the get go. Stay away from Sand sifting predators like sand sifting goby's too. They might look cool, but they will eventually "clean" your tank of all the critters you need.
Visit Reefcentral.com if you haven't already- I know this is reefs.org and it's bad to try and divert attention from here, but come on- there's alot to know about reef systems, and the more information, the merrier.
How did I do on my very first post on reefs.org?
I'm sorry if any of you out there disagree with me about anything I've suggested. Some of it makes since, and some of it doesn't, I know. Please don't flame me because of what I suggest. I'm not trying to say that any of you guys out there are wrong with doing some of the things that I don't suggest. These are just in my opinion.