The secret to preventing muscle loss is to lift weights and to keep your calories high enough. You still need a negative calorie balance to lose fat, just don't overdue it.
The type of weightlifting you do is a matter of
personal preference. If you are just starting out, I would probably recommend a full body routine 2 to 3 times per week at an intensity that is hard, but not too hard. Focus on proper form and technique.
For cardio, I've always preferred steady-state over
high intensity, at least until your body gets adjusted to the new strain. Adding HIIT later can be a good way to re-start progress in the future. I'd shoot for 3 cardio sessions for about 30 minutes per week to start with. You can add duration and frequency as you get further along. If possible, try to separate the lifting from the cardio.
For diet, what a-welch recommended can work. I personally went with a diet higher in carbs and lower in protein (approx. 55c/25f/20p). The best diet is the one that you can stick to. As long as you maintain a negative calorie balance and exercise, you will lose fat.
IMO, the most important factor in successful fat loss is the ability to set, adjust, and meet goals. If you can learn to focus on fitness goals, you will have greater success.