Tristan got it right.
You stop looking for someone else, by focusing on yourself instead.
Learn to love yourself, accept yourself, etc..
Better yourself, know yourself, etc...
And try to learn that there isn't a soulmate out there.
There is no relationship that doesn't take commitment, hard work, and a lot of energy, from everyone involved, to be a "good" relationship.
The only person that can complete you, is you.
When you find that person, you want to be a "complete" person, capable of having a functioning relationship anyway, so working on you now is a good step towards having a "real" relationship later.