For fat loss it's, long and slow wins the race !.
Intensity is actually not the key factor in weight loss, but however it should be introduce as it also helps to add stamina. For increased and lasting stamina an increase of only 10% in both distance and effort should be introduced from the start. This has been shown to give last results should it be neccessary to take an break through injury, sickness etc.
For maximum fat loss the cardio should be done an an empty stomach. Only thing which should be taken before hand is water and nothing else, then don't eat for 1 hour after the cardio session. After which take in a proper ratio of protein,carbs and fats.
If AM cardio proves difficult, and it is for most !. Try not eating for 2-3 hours before your cardio and 1 hour after. It sounds harder than it actually is, and the quick results are great.
Lastly don't forget her rest days, their very important and can't be stressed enough. Especially for a beginner.
Bouncer