Well, I am not really shy and not all that interested in casual friendship. There are many profiles of women that I look at, and am interested in, that I don't initiate contact with. This is due in large part to them living relatively far away(more than 4-5 hours drive let's say).
When I do intiate contact, though, if the woman doesn't respond, I am not likely to send another until she responds to my first. I DO NOT want to be a 'stalker' type/annoying to a woman that, as far as I know, isn't interested.
I don't mind pursuing, but I don't want to chase. After I initiate contact, if the woman is interested, then reply!!! And if I contact you after that, reply!!! Don't make it difficult!
One other thing, don't assume that if I guy has looked at your profile and not messaged, emoted, etc... that he is not interested. Many times I may look at a woman's profile, be interested, but 'mull things over' in my mind, trying to decide whether or not I want to make a move.