Computer Building Business

I was just wondering if anyone here had any tips on my starting a computer building business. Where do I start? How do I start? Where do I advertise to where I will actually get a customer? I already made an estimate on a computer for under $750 with parts that actually work from reliable and sufficient companies, but I already know I can add up numbers and give estimated prices to customers. How do I get the customers, though? Any other topic/question I missed please enlighten me. I’m only a college sophomore and this is the thing that I can do to make some money from what I’m good at.