I'm not an expert but i'd recommend a combination of intense aerobics/cardio + strength training. The aerobics will burn off the fat & strength training will build muscles. Be sure to eat as healthy as possible making sure you get plenty of low-fat protein (chicken, fish, & beans are good options). Drink lots of water & be sure you get a proper amount & quality of sleep. I hope that helps & I wish you success in your goals!
I also have gained some weight but my focus is build muscle, eventhough not bulk... Circuit works for me... Plank, Squat, Lunges, Overhead Press, Push ups, Power Clean with dumbbells are some of the moves I do, one following the other without rest... in about 30 mins I feel I've done cardio and strength at the same time!