I've been printing my comic issues for a few years now. I realized through my journey that it's extremely important to shop for the printing company you want to deal with. Prices vary and some can be crazy expensive, while others will give you the best quality & price. As many of us tend to buy online, a lot of online printing companies might feel worthwhile, but I suggest to check out your local businesses. I can tell you from experience that with all the research I did years ago, I actually found a local company that gave me the best quality, service and price.
Just like @darthmongoose said, it's very important to market yourself, so getting convention tables is a must. I don't have a don't have a ISBN yet, I'll wait until I have a volume. For right now, I only have 4 issues out. I haven't quite figured out the shipping aspect of selling online, so that's still a work in progress. However, in my case, I was able to bring the comic series to local stores in my province with a consignment agreement. I currently have it in a total of 3 stores, in 2 cities and a town.
It still fairly expensive to print a comic book. Especially if you're dealing with a full-coloured one, like I am. I actually sell my comics for $10 each. That might sound expensive, but it also depends where you're from. I live in Canada, so nobody has ever complained about my prices and if I go too cheap, I won't cover my cost. I've had no complaints about my price, I would sell cheaper if it was in B&W, but colour is expensive.
Oh! Print in quantities, a lot of printing companies will offer a discount after a certain about of copies. But, don't go overboard either, depending how much space you actually have to store these boxes. Having a huge order for the first comic sounds like a great idea, until you have to store them somewhere in your home. And, when it comes to the other issues coming out, you have to store them too. I have a box worth of comics at a time. Thank goodness, I have 4 issues out and a 5th on the way.
I don't have many online readers, but as I've been told many times by people. They prefer waiting for the book to come out. The series actually does well in book form.