I have spent some amount of time on dating websites and have met alot of freinds and interesting people myself, although I have yet to find exactly what I was looking for, one thing I have learned for sure is that there are an awful lot of people looking for just one person to love them, even people who are in a commited but loveless relationship. I felt that before I can appreciate another person, I should understand how great it is that I have ONE wonderful person in my life far more than worthy of my love. That gives me a sense of peace and patience in searching for the second.
Well my best advice is not to just think that someone will walk up to you and say "yes, I will be the second love of your life". (Could happen, but...) There is some "getting to know" and just like finding the first love there may be some trial and error, but the journey itself can be much fun. Just stay honest and know when to call it when it isn't working out.