I find it somewhat hilarious that everybody is proffering advice on "what next" without asking what your objectives are. Programming? Art/imaging? A general development environment? (Office/productivity/business apps? Games?) Desktop? (Wrong choice of OS though...)
Assuming your intentions are to use Linux as a solid development environment for games (since this is, after all, GameDev.Net), what kind of games? Real-time 3D? Board games? If you''re planning on doing computationally intensive, close to hardware stuff, I would endorse suggestions to go get the Simple DirectMedia Layer at http://www.libsdl.org because it both simplifies many operations and provides free code portability (theoretically just a recompile).
If you''re planning on writing something less complex (media-wise) such as a desktop puzzle game (Minesweeper, Solitaire, Tetris, etc), the question arises as to which desktop environment(s) you wish to support. There are different development toolkits for each of GNOME, KDE, FVWM, AfterStep, WindowMaker and so on, with varying levels of interoperability (ie, GTK+ apps work fine to an extent under KDE, but look horribly out of place; KDE/Qt apps may be unable to respond to certain GNOME messages). Choose wisely. Of course, total compatibility is possible by using "vanilla" toolkits such as Qt alone, or Xt.
Anyway, once you''ve decided on your targets, begin to learn the technologies necessary to fully utilize them. manpages are your friends for many things, info for many more, but recent apps come either with HTML docs or none at all (sadly, Open Source/Free Software developers regard documentation as a necessary evil). Realize that using Linux involves a lot of learning, studying and experimenting.
Learn the UNIX way of doing this: small, simple tools that employ a standard interface and can be chained together via piping and so on. The same should apply to subsections of larger applications - behemoth singular monstrosities are EVIL and must be DESTROYED!
Above all, kick back and have fun. Linux is an _alternative_ OS, so just take your time and don''t put pressure on yourself to produce something very soon. It will come.
Those who can do nothing criticize; those who can, critique.
