As with any "fat burner" containing active ingredients like Ephedra and Caffeine (or their herbal equivalents) you need to assess yourself for tolerance first off. Then you need to drink lots and lots of water while using whatever product you are trying. I mean, 4-6 liters a day to keep your body functioning properly and responsive to the E/C.
You also need to keep your house in order for best results. Eat clean relevent to your dietary/workout goals, get lots of sleep, lower stress and don't forget to lift weights to build your basal metabolic rate.
Also "cycling" your E/C will give you an extended stimulatory effect.