I play single player mode long before playing a game online.
That method helps me learn the ins and outs of a game before being exposed to the online community.
For Example, I downloaded but didn't play the Red Alert 3 Multiplayer Demo. Wanted to TRY the units at least in a sandbox mode NOT to be thrown to the dogs to learn the game online. Since there was NO Single Player Demo to learn the game at that time... so I didn't purchase the game.
Have played too many games that just didn't live up to the hype... bought a few without trying the demo first. Never again will I pay for a game without FIRST Play Testing it.
Purchased many games that I normally wouldn't have purchased because the demo was so well representative of the game play.
Unreal Tournament was purchased because of the outstanding Single and Multiplayer Demo.
Descent 1 demo was one that I played and deleted a lot of times before purchasing it as part of Descent: The Definitive Collection which included Descent 2.