The effect of GH can be very mild compared to steroids and compared to what the media would like you to believe. The name alone, "GROWTH HORMONE" sounds like it would be the answer to all of your problems, right?! GH can have a really great effect, but results are going to depend on some factors. Dosing, length of use and brand are the major ones. If you want the very best, you'll want to go with pharma brand. Pricing for that can get to be very expensive. I've found good results using the top generics. Hyge is what I usually suggest here on the QA. More expensive than genetic colored top GH, but far cheaper than the big name brands. For dosing, 2-3iu will be good for replacement. 4iu is good for fat loss. 6iu or more, will help with fat loss and muscle gain. Keep in mind that muscle gain from GH alone is going to be minimal without the use of test and possibly other AAS. For the best gains, the very advanced guys will use GH. AAS and insulin. Thats where the big gains come from. Insulin allows you to use more carbs and high doses of GH 5-10iu, will allow you to stay lean in the process. For cycle length, I would stay on GH for at least several months, if not longer. Ideally, you'd want to stay on it for years at a time. The effect is slow but over time, your physique will transform. 

If this all sounds like it might be beyond your level of experience (Which it is for many), understand that you can do reallty well a few IU while cycling on and off for a year. If you want to gain muscle, rely on your steroids and use the GH for overall quality of health and to aid in body fat control.