Testosterone can be administered parenterally , but it has more irregular prolonged absorption time and greater activity in muscle in enanthate , undecanoate , or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system.  Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
You will have to use HGH in a pulsate manner, meaning injections taken every second day gives better results than daily injections. Rather use the higher end of the dosage range on these days. For instance, instead of using 3IU's daily, rather opt for 6IU's every second day. Dosing should be at periods not close to sleep or training sessions, or close to supplement ingestion containing Arginine, OKG or GABA. It’s more effective to use it early morning and later again before lunch. Follow each dosage by ingestion of at least 50-60gr high quality hydrolyzed whey protein, taken in at temperature of about 4C this will improve gut emptying and by the time the IGF-1 is released to the gut, your whey is available for absorption. Do not use Insulin around the same time as your HGH, neither use IGF-LR3 or MGF close to HGH dosing.