I'll be shooting headshots for other models and fashion photography.
Base talent shots just need to be evenly lit, but a portfolio needs to be lit correctly for the shape of face- lighting is more important than camera- a set of strobes, modifiers, triggers and gels, as well as an understanding of lighting is important. A competent MUA helps immeasurably as well once you get past the flat 8x10 w/o makeup most agencies require, and a couple of basic backgrounds and stands are a good place to start.
Fashion depends heavily on usage/market/age, but as well as lighting, posing skills, lots of space, long super-teles seem to still be the look of the day for lots of fashion work- depending on what markets you're competing in. Good selections of matching accessories (earrings, bags, scarves...,) makeup, glycerin and other props help a lot if the clients aren't going to furnish everything. Strobes, modifiers, power packs for outdoors, sandbags, the ability to get location permits if you're in a restrictive jurisdiction... again the camera body is really secondary unless you're shooting high-fashion, in which case you're basically looking at the Hasselblad HD-39 along with all the lighting. A good MUA becomes more important as you start to bring in fabric colors. Good color profiling is important too- being able to manage everything from lighting temperature/white balance through workflow gamut to printing profiles tend to be important in fashion.
Good contracts and good insurance are also more important than which camera body you shoot with.
Neither of these fields tend to be "I only shoot natural light" type events by a long shot. I'd recommend some time at the library looking over some fashion photography books, posing technique books, lighting books, and color workflow/printing books as a good start. Also, unless you've got a good-sized studio to shoot in, you're going to want to have relatively powerful strobes for outdoor work- the cheap "Strobist" type set-ups don't tend to work well when you're dealing with a lot of ambient light. Additionally, a good flash meter will be helpful in dialing in initial ratios.
I'd avoid anything that's not a constant f/2.8 or better unless you can get outdoors with backgrounds way in the distance. Crop factor bodies make it a little difficult to get that telephoto compression look due to magnification, but if you're not doing a lot of extreme close-ups it may not be that big a deal. You do want something that's reasonably long though.
Fashion is one place where finding a good series of courses or workshops is well-worth it.
