When it comes to appearance you are usually talking about muscle definition. If she has reasonable muscle mass now, the key is really nutrition to help reduce body fat and show definition. Obviously you need to keep building muscle mass, I would make sure she is doing 2-3 days a week of HIIT (aerobically) to help, and make sure she is getting adequate rest. But at this date I would say nutrition is the most important factor.
I agree with Janet – it’s coming down to diet with that time frame. I would go with a moderate calorie reduction in those weeks & hold the course with the training. It’s a tough question to answer without seeing her or knowing where she’s at as far as body fat % goes. Off the top of my head, I would assume that she would need to be around 10 – 15% body fat (maybe slightly more) for a contest like that.
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!
Also, here are a few links and examples that may help you: