There are four basic steps I can think of.
1. Become a "me expert"
In other words you have to know what traits you want or need in a mate. Essentially this requires doing some serious introspective thinking to figure out who (you) are and what you need in order to feel happy. People who don't take the time to do this generally allow "impulsive connections" and "happenstance" to dictate their relationship choices.
It's the equivalent of going shopping without a list!
2. Create a profile of your ideal mate
You want to be as granular as possible. Does he/she live in the city or suburbs, work out at a gym (large or boutique), shop for clothes at the mall, independent stores, or Wal-Mart, What are their hobbies/interests, occupation, sports enthusiast (which one), attends church (if so what denomination), shops for food at a large grocery chain or a boutique health food store? Would they join an online dating site (if so which type free/pay) ..And so on..
Most people have no problem making "lists" of traits and qualities they want in a mate. The goal of this step is to (imagine you are the person that you want) and ask: "If I were him/her would I want me?"
If the honest answer is "no" then you need to go about cultivating the traits and qualities (you believe) this type of person would be attracted to.
"Don't expect to sit next to the moon unless you are a star!"
4. Be There!
The only way you're going to meet your ideal mate is to be where they're at! You have to run in the same circles. If you were very detailed in step 2 then you should have a good list of possible places where you might meet. However other factors come into play such as your personality, appearance, and ability engage in conversations with new people. Those who are very introverted will have a bigger challenge finding a mate because their real goal is to have someone "find them"!
Lastly it's important to be "realistic". Anyone who is a teenager or in their early 20s is probably being naïve if they are expecting to meet "the one" at that stage of their life. There are "exceptions" but the vast majority of people in that age group aren't in a hurry to become their parents! The last thing on most guys minds during that period is getting married, having children, and signing a 30 year mortgage! That's the equivalent of watching their lives flash before their eyes. Their goals usually are to have fun with friends, explore/travel, casual dating, and establish a career path.
A young woman in her 20s who is looking to be married may do better to date single men in their 30s who are likely more ready to settle down. One man's opinion! :)