I take the approach of assuming I won't get a response to my messages, and send them out to people I find interesting. When I do get a response it's a pleasant surprise every time, as I have a new person I can get to know, and maybe establish a connection with. In a sense I think I prefer just not getting a response, because I don't need any excuses or to be told someone isn't interested in me. I know who I am, and am proud of that. If someone doesn't respond, that's their choice and as I said earlier, it's easier to assume they're not interested. I'm not saying this works for everyone, or feels great by any means, but there doesn't seem to be an established online etiquette and even Catholic Match a while ago had a blog post about that exact thing and how online dating sites are still relatively new, so firm rules on how to deal with messages and such aren't firmly established.
Just keep your head held high, be proud of who you are, and do your best. God willing, you'll find the right person, either through here or in real life. Either way though, I'll pray for your success.
Good luck. God bless.