Though I had an SLR for nine years, never experimented much because of, you know what! Cost!! Now that I moved to DSLR and three lenses - 18-55 + 55-250 + 50mm 1.8 - I have got enough resources to play around for free ( already paid for:-) )
I got the most flattering results with my 55-250 telephoto zoom at around 100mm WITH NATURAL LIGHT before noon - indoors. I stand next to the window and I ask my subject (so far only my wife) to stand facing me (window). I can not post these photos as she didn't agree to.
Cut the crap - my personal style is to focus as close as possible with just the face filling literally the whole frame - if that suits you. The results are usually very flattering. Try it.
General technical data I used:
Canon XSI with 55-250 at around 100mm
1/2 sec - 1/50sec