Tbh, I think that the wink and favourite functions are really lazy. If you like someone, then send out a proper email that shows you have read their profile. A wink and a favourite just mean, I've seen your photo and it doesn't immediately put me off the thought of fucking you... so they favourite/wink either to come back and look at your profile later, or to see if you'll pick up the bait and email yourself. Ignore anyone who makes contact with you when you don't have a photo and only have the basic profile completed.
Don't worry about the etiquette of online dating, or about seeming rude/aloof/unkind, or agonise how to reply to contact from a man you don't find attractive. Some men will send out winks/favourites/"hi sexy" emails to many, many people, 20-30 in one sitting maybe. It doesn't really mean anything, and the brutal truth is that whilst you are agonising over how to let him down gently, he's already forgotten he sent it. I would always respond to someone who sent a 'proper' email to explain I wasn't interested; that's only polite.
Don't forget you can also search for new members. A lot of men will do this because they also know new members will be naive to the ways of online dating, won't have such strong boundaries, and are more likely to respond favourably to very little effort.
Don't get me wrong, there are no doubt some very genuine and decent men on there. I've known some, and I've also been to a couple of online dating weddings, so I'm not completely cynical. But you need to go into it with your eyes open. If you go into it with the view that online dating is full of men looking for love and a long term monogamous commitment with a special woman, then you are going to get hurt and be very disappointed.
There are some 'rules' on the first page of every dating thread on here. They are not to be taken lightly, especially (from memory) the one about having thick skin, the one about people disappearing and generally being weird is not your fault and the one about it all being bullshit until it happens.
The photos will tell you a lot about a man's intentions and whether he is available or not. Be ruthless.