A lot people make their living off of building and submitting galleries, but I submit very few because I find it to be so damn frustrating. I'm not even sure why I find it so frustrating, I just do. It may be the minor differences in rules from site to site, but overall the rules are the same. There are always variables that are out of your control. You can have the fastest host on earth and someone's script is going to reject you for slow server response. You may build the cleanest galleries known to man, but you are going to get rejected for HTML errors. Shit happens. You roll with it your it rolls over you.
My suggestion is to just work your way in slowly. Read and post here whenever you can. Ask a lot of questions. A willingness to learn before you leap can do wonders in the long run. Newbies get banned everyday for simple easily avoided mistakes. It's not because the site owners are hateful. It's because they are too busy to keep weeding through someone's repeated errors.
As far as content goes, Selena said it best. Purchased content will get you much further than free sponsor content. It's not only because the content has been seen so often. Much of it just sucks.
Find a reliable host that you can afford. Avoid everything that has the word free attached to it. Try and use only .com domains. Avoid .biz, .info, and the rest of those cheapies. If someone already has the .com you want, go back to the drawing board and come up with another.
Go forth and prosper.
