The majority of the game lies in group content. It's an MMO, after all. If you simply prefer playing alone, you'll have less to do.

That said, if you choose to do so, a LOT can be done solo if you've got the chops. Good dps helps a lot of situations, but the most important tip I could offer is to learn mechanics. Understanding how things/enemies/encounters operate puts you in the top tier of players pretty quick, as most people just charge into their playtime near blindly. Be observant, look up guides on things that are stumping you, and you can definitely get your money's worth from this game.