If you want create a bitcoin mixer, you should make a good looking site because it is very attractive to the users of bitcoin and most of them like minimalist looking site and also include a lower fees than the other bitcoin mixer so you can get more customers and also do some campaigns like signature campaigns to spread your site and easily get popular around our forum.
How exactly does one set up a signature campaign?
It's very simple and cheap if you have the time to manage it yourself.
You make a thread in the services section with all the rules, payments, make a list of participants in google docs. You'll need to make a signature. A simple one without special characters can be made in minutes. If you want an advanced, more flashy one, you can always pay someone to make it, but a normal one will work just fine.
Next you set up an escrow if you want the campaign to attract more people and you're all done. Provided the rates are decent you'll have people advertising your service in no time.