I like the quality of gaffs that I've purchased from Janet's Closet
http://www.janetscloset.com/index.htm has a nice selection of gaffs that are very comfortable and will conceal everything "down there" very well. For me gaffs are a much more comfortable alternative to "tucking" a technique I've never gotten the knack of!
Besides her website, Janet alsp has a store in Wyndotte, Michigan with everything a crossdresser or a t-gurl needs for her transition. Her site also has some good information about transitioning and legal stuff regarding changing your name etc. I buy these sexy gaff that she sells to hide my stuff.
This is a photo of me wearing one of her gaffs that also serve as a nice thong. As stated, the gaffs work pretty well and are more comfortable than "tucking". One night I was in a club chatting with a guy at the bar. He got a little bold and put his hand on my thigh and eventually "down there". The gaff was wearing under my low cut jeans evidently hide my cock pretty well as he looked shocked when he couldn't feel anything between my legs. Later he got lucky and discovered that I am very intact "down there" and quite functional! His ass was a little hairy for me but quite tight!