The best way to get a date is to ask for one.
First You Have to Ask
Sure, there ways to make your success rate higher, but consider that the more times you get the courage up and ask someone out on a date, the more likely you are to get one.
Obviously you should not be hitting on everything in sight, but if you see someone that you like go up and say hello. See if you can talk to them for a while and if you are getting along, tell them you enjoyed the conversation and would that you would enjoy their company again. You don't necessarily have to set a time and place right then. If you get a phone number, you can set up a date at some later point.
Numbers are in Your Favor
The more times you ask people out on dates, the more likely you are to find someone who will say yes.
Practice to Improve
Another benefit of asking people out on dates is the more confident and at ease you will become on your next attempt.
Learn From Your Attempts
Don't take it too personally if you are knocked back when asking for a date. Perhaps you were just not the right type for the person you asked. Analyse successful and unsuccessful attempts to get a date and refine your process.
Read the Situation
If someone is enjoying your company and they are not attached, it is pretty likely they are going to say yes if you ask them if they would like to see you some time. Just remember to be graceful when asking for dates. Accept that some people will say no and do not become aggressive or insulting if you are refused a date or phone number.