I used a 28-105 for these shots but sometimes I switch to 50mm, 85mm or 70-210. Up till 6 months ago, I was using a compact and when I bought my dslr I initially used just my kit lens. So I am still a newbie.
Your equipment is fine for starting off on model shoots. Your lens is versatile and will allow you to try various focal lengths for different perspectives. Joining group shoots will let you meet other photographers who will be willing to give you better advice than I can.
You can read books, magazines, even advertisements to get ideas of poses but the best, short of taking a course, is join a group shoot. The advantage of a group shoot is that there will always be someone who will select the scene and pose the model. Experienced models can autopose but they need an idea of what you are trying for. Even then, they can't see themself as you would through your viewfinder and need you to correct them if something is "out of place". Lastly, don't worry too much about it - just join and shoot. Hope this helps.