Small business startup advise

Right so right now I'm taking an education about computer support (frontline pc supporter), and with that I really wanna start up a small business where i build, sell and support computers - primarily gaming ones. I'm really just looking for any advise.

Also, I should say, fiddling with computers aren't just an interest for me, it's a passion, I love doing it, and my ultimate dream is to get a small business up running, where I just do computer stuff - It's what I love doing, more than anything else.

Yeah, In Denmark where I live though there isen't really that many of this kind of businesses, so yeah.