Sounds like you have no experience with any of this brother and havent dont any homework. There is so much info online that there is no reason that anymore shouldnt know how to use these things. I would suggest that you learn as much as you can. I feel torn answering this because I am enabling laziness. The shot answer is no. You cant use the same syringe. For AAS injects, see this : 

https://juicedmuscle.com/showthread.php?49-A-Guide-to-Safe-Injection-Technique

For GH, do a search on youtube and you will find 100 videos about how to mix gh with your bac water and how to take it. I would take it IM verses Sub Q, btw. 

So if you have test, hopefully you have a good AI and planned a PCT. If not, you will have nothing to protect you from the very real dangers of testosterone. 

Im happy to help, but I want to see that people at least put enough effort to figure the very basics out on their own. Then once you think you have it figured out, I would be happy to double check with you and make sure that you are doing everything as safe and effective as possible