Looking to get started, but I need more than ideas to get going

I want to start out selling a few shirts (maybe 4 or 5 designs to being with) and I have some ideas that I really like.

Basically, I want to sell to high schoolers/college students. It will be mostly humor based shirts, plus some political stuff (since those tend to sell well), and I was even thinking of adding school-specific shirts (copyrights are an issue, but some schools are lenient).

I want to sell quality shirts. High quality. Nothing that feels weird or doesn't fit quite right. Stuff that is fit to sell in an actual store, where the customer can see it and try it on so they know it's good. I don't plan on opening a store like that, but that's just how good of quality that I'm aiming for.

So with that in mind, what kind of process of printing am I looking at? And what do those machines typically run at?

Also, how do you guys handle shipping? Is there a place where I can order custom packaging, so I can make it more personal?

And a random question: How does 6dollarshirts (not trying to advertise so if this is against the rules just let me know) manage to sell shirts for so cheap? I want to sell my shirts around $10-15, since more places tend to charge $18-20 (need to run some statistics on that to make sure), so therefore I am cheaper and maybe that brings me an extra couple of customers a week or something.