well, there is a choice to be made, do you want to watch everything in the order of the star trek universe (Ent, TOS, TOS movies, TNG, DS9, VOY, TNG movies) or watch it on the release times. TOS, TOS movies, TNG, DS9, VOY, TNG movies, ENT.
I don't think it really matters in what order you watch things. I started with voyager last year, then TNG, DS9 and now ENT. I did the movies spread across all the series i watched
Maybe one of the older guys around here can give you a different view on this