I don't own a dog but want to be a sitter, is that OK?

I think sitting is a great way to get to hang out with dogs when you don't have the time or resources for a full time dog of your own too!

Definitely OK. I don't have a dog either because my family doesn't want pets (if I was able to have one, I'd already have one a long time ago). That's one of the reasons why I want to dogsit - so I can hang out with dogs since I can't have one of my own. Not having a dog is good for traveling sitting because you are more free and don't need to go home to take care of your own dog and it's good for boarding dogs in your own home because some dogs might be not like other dogs.

There are plenty of dogs out there who are most comfortable when they're the only dog around, and they wouldn't be happy staying with a sitter who already has pets. And of course if you're sitting dogs who love other dogs, you can always try and meet up with friends' pets or hang out at a local dog park (with the owner's permission, of course!) so they can get that canine interaction while staying with you.

You would also be in a great position for travel sitting, since you don't have a dog at home that needs your constant attention.

Point being, providing a home without other pets is a necessary service and would be very welcomed!