Make sure you get the real thing. Buy it from a reputable source, and don't just go for the cheapest shit they sell. Some sources will sell HCG and claim its HGH. I've heard a lot of people suggest taking the HGH you bought and put a drop on a pregnancy test to see if its HCG or the real thing. Unfortunately, its harder to tell if HGH is the real thing or not since it can take a good while to start seeing results, unlike substances like Testosterone.
Also, you should know that HGH is a very powerful tool in a BB'ers toolkit -- when used properly. If you use HGH by itself, you're wasting a HUGE amount of potential. HGH alone will cause LBM to increase and assist with fat loss, buy you will get far superior results when you pair the HGH with at least another steroid. HGH is so expensive compared to steroids, so why not just use it alongside some steroids for a much more effective stack?