Yeah, what others say.
If you decide to go for
ComicGen or
DrunkDuck as a host, you don't pay but you don't have a chance to make money, eventually, if your comic gets popular enough for that. On the other hand, many start on ComicGen and when they earn enough readers to make it worthwhile, they move to their own hosting.
Webcomics Nation charges for hosting, but they let you either sell adds on your pages or make your comic subscription-only. Frankly, since there's a large portion of comics well drawn and still free for view, I don't think that subscription method works unless you're a well-known comic author who knows that there are people who'd pay to see his stuff; Adds, on the other hand, won't get you money unless your site is visited a lot, but since your comic is free for viewing in that variant, you'll be gaining new readers easier. In any case, you'll be paying a host with no real guarantee that you'll make money out of it, which is why most of people who do it as hobby, start on one of free hosts.
There is
Keenspot and
ModernTales, a sort of elite sites; Generally, they'll pick you if they like you; It's a "don't call us, we'll call you" deal. You can still sent a sort of application letter to them (specially Keenspot) but they're pretty picky and they'll probably want to see how your comic is doing on site before they accept you; Which means that you still need another host. As for Modern Tales, someone mentioned that their branch for action/adventure comics
Graphic Smash is accepting submissions right now, but I couldn't find that information anywhere.
There are a lot of other, smaller webcomic hosts, their rulles of acceptance vary from case to case. Lots of people around want to make their webcomic communities with hosting included. One that I know of is
Xepher. Their rules on whether you can attach adds or ask for donations vary too.