@Limaloma1 When I was using POF I always kept my profile hidden, then either favourited (is that a word??) guys I liked the look of, or sent them a message if they had an interesting profile. I really couldn't be doing with all of the "hey, pretty lady..." standard messages that 99% of the men that approached me first sent when I didn't have my profile hidden. I felt much more in control having a hidden profile. Of course, the guys can always see if you've viewed their profile and may contact you anyway, even if you decided they weren't for you after reading their profile.
Don't feel bad about blocking the creepy ones straight away, you don't need to justify yourself or give them a reason. As for conversation tips, finding a common interest always helps, even if it's just a film you've seen recently/comedian you like or place you've both visited on holiday.
As I said earlier today, I'd really try and avoid messaging for weeks without meeting. I got horribly over invested twice with guys I'd never met. One ghosted me and it shot myself esteem to pieces (funnily enough, we're now in contact as friends and he confessed that he thought I was completely out of his league which is why he cancelled 3 dates and then ghosted me...) The other guy I had such a good time with online and over the phone over a 3 week period, but when we met, there was no spark at all. I couldn't believe it was the same guy, 
and actually felt quite a fool that I'd let myself develop feelings for someone I'd never met. You live and learn I suppose.
Sorry, that was a bit of a brain dump 
