I have never trained anyone for a fitness competition, but from what I do understand about them, the training is very specific and very intense (not sure if 6-7 weeks is going to be long enough). I believe there are bikini, figure, fitness, and bodybuilding classifications–and the look is different for each one. There is a lot that goes into preparing for a contest–nutrition, the workout program itself (including body fat percentages for bikini competitions), and actual prep for posing. The look for a bikini contest is “softer” than for other competitions. Fit and lean but not too muscular. The look is very specific, and they will be judged on things such as muscle symmetry, proportion, shape, etc… If they look too muscular they may have points deducted.
I hope someone else on this forum can give you some specific pointers because of the detail that goes into preparation. If not, perhaps you could reach out to a coach in your area familiar with these competitions–or do a lot of research on the topic.
Good luck to you–and your client! I hope you both do well!