Don't wait until you need something
No one likes someone who is trying to build a relationship just to benefit themselves.
Unfortunately, this is what many people do when they start "networking."
The worst way to build a new relationship is to meet someone and then ask for something right away.
It will turn them off and make them NOT want to help you.
However, if you can build the relationship before you need something, and ideally, are able to help them first, they will want to help you if/when the time comes.
So start early, give first, and then only when you have established a good rapport, ask for their help.
Want the full playbook? Check out Going 1099.