If you find out about photoshoot opportunities yourself here are some helpful tips and things to avoid:
Don't take anything for granted. Check out the photographer first and try to get some references from other models/agencies. Always verify the credentials of a photographer. If he says he shoots for a certain magazine you can call the editor to check this.
Remember: if it sounds too good to be true, it usually is.
Again, Make sure you tell the photographer that someone knows where you are.
If you decide to do semi-nude shots, be sceptical of photographers or scouts who want to shoot frontal nude photographs of you for any reason, especially within a TFP arrangement. Some artistic nude or body shots can enhance a model's portfolio but only if the model has an appropriate body and a photographer who can capture high-quality images.
If you're not willing to model nude (and many models are not), then don't put nude images of yourself on your portfolio. Make it as clear as possible on the exact types of jobs or assignments you are prepared to except.