Basically if you've already calculated your BMR then start at that number and if progress slows you have two options: slowly cut calories or increase cardio. When I say slowly cut cals, I mean 250 cals or so daily until you're seeing progress again. Cutting calories too quickly is usually counter productive especially since you are trying to hold onto your muscle mass.

In all honesty, carbs are not a neccessity when cutting. You could try completely cutting them out or if you feel like you need them, time them around your training only. If your taking this approach I would recommend giving yourself a refeed once a week to restore glycogen. This will help fuel your workouts throughout the week and help with making yourself not look so "flat" due to the lack of glycogen as the week progresses. The carb refeed will actually boost your metabolism and help your progression as far as fat loss goes. Keeping protein intake high will also aid in preserving muscle. At the bare minimum, you be consuming at least 1g of protein per pound of body weight.

Use the below macronutrient information to form your meals to reach your target caloric intake:

1g protein = 4 calories
1g carbohydrates = 4 calories
1g fat = 9 calories

This should be enough to get you started, plenty of other information on the subject can be found on the forum.