Generally, getting in shape for most people means losing weight more than anything. It should, however, really mean losing weight and maintaining as much muscle as possible (or building more muscle). For a lot of women, they have it in their heads that if they lift weights they will suddenly become big and bulky and look manly. This just doesn't happen. Big and bulky is a function, to a large extent, of testosterone and most women don't have the genetics or the levels of testosterone to naturally become huge, especially without great effort. Even as a man with (presumably) normal testosterone levels I have to work incredibly hard to put on any muscle mass.
Having said that, I would incorporate a simple weight lifting program 2-4 times per week with the goal of actually gaining some muscle mass. If you put on 5 pounds of actual muscle, you will be surprised at how this improves your tone and overall health, not to mention the mild increase in metabolism you will experience. I would keep your workouts intense and brief, but some one here may disagree with that. I think working hard is the key though, period. It isn't how long you work, it is how hard you work.
Diet - here are some simple rules that I am stealing from Elliot Hulse and paraphrasing a little:
1. Get quality protein - lean beef, lean chicken breast, eggs, fish, milk, non-fat greek yogurt, non-fat milk, non-fat cottage cheese are all good sources of protein. I would get somewhere between 1-1.5 grams of protein per pound of bodyweight - so about 150-225 grams of protein. By no means would I ever drop below 120 grams/day.
2. Water - Drink 1.5 - 2 gallons/day. Stop drinking anything but water.
3. Veggies - green veggies in particular. Eat all you can stuff in your face. Bags of broccoli, spinach, green beans, lettuce, etc. - these are low calorie foods with TONS of mass that will fill you up and give you many nutrients and you can eat to fill yourself up. Stay away from carrots, potatoes, etc. Stick with the veggies that have, say, 30-50 calories/cup or less.
4. Walk - Elliot recommends just walking to lose weight, which is a good, low-intensity exercise that burns calories and won't burn a lot of muscle.
Some things I would add to this, maybe 2-3 HIIT workouts/week would be beneficial. If you have to choose though, I'd go for the weights. HIIT can be completed in 20 minute sessions though, and be very effective.
Fish can provide quality fats that your body needs and you should take in. If you don't eat fish, consider supplementing with an Omega-3 supplement. It may be the only supplement you should get at this point.
Another good fat, in my opinion, is coconut oil. I cook all my eggs and chicken in coconut oil - but it has to be virgin coconut oil. This provides a type of fat that is beneficial, burns easily for quick energy, and may actually speed up fat loss. It may also be good for your brain. Don't go nuts with it, I can cook 3-4 days of chicken in 1-2 tablespoons of coconut oil. 1-2 tablespoons/day is acceptable.
Those are the simple rules that I can think of. I hope it's not all too much. Please keep in mind that I am not a doctor also and I am assuming you are otherwise healthy and this should not replace the advice of a doctor. I am just stating some of the methods I have used and do use that I feel are simple and effective.
