Cultivate connections with people you know and trust, rely on their connections instead of trying to force connections with people you don't know.

The power of linked in isn't building a giant list of everyone who is related to you, it's building a tiny list of really awesome people who have a tiny list of really awesome people who have a tiny list of really awesome people...

TL;DR: If you curate content, don't be surprised if the quality rises.

EDIT: This is the perspective of a more introverted type who tries to build fewer strong connections instead of many weak connections. If you can build and maintain many weak connections effectively, go ahead! I just know that I absolutely cannot maintain those well, and prefer to network with those who can and rely on them to maintain those connections.