There is mounting evidence that the more frequently you crossdress, the further along the continuum you will find yourself moving.
Transvestites can roughly be split into three groups, with those in the first group not going beyond putting on a few women's clothes and maybe a little makeup in private, and getting a kick out of it.
Those in the second group, will feel the need to look like a woman and will wear women's clothes for extended periods of time, and will even go out in public and hope to be taken for a woman, but they never wish to actually become a woman.
The men in the third group fringe on trans-sexuality and will spend much of their time in women's clothes and makeup, and the only difference between these men and full blown transsexuals is that they don't want to actually become women.