Well you should start low, don't start with the most sophisticated stuff and don't try to add many features at once, but one-by-one.
Make yourself a to-do-list and plan ahead before your start to code (that's very important!).
Maybe begin with selecting an engine such as SDL, OpenGLES, etc.

(and you might want to tell us as we could give you more specific advice and links).
Then go ahead by trying to render basic images, then implement some sort of collision, then bad guys, etc.
Your first results may not be good or even decent (they might not even resemble much of a game

), but don't give up early. The first and last steps are the hardest and most boring (getting started and final touches).
After you passed the first few obstacles and get a controllable object rendered on the screen, things will get more interesting as you can start to implement gameplay.
Just don't try to bite more than you can chew, start really low (as described above) with the player, some test enemies and a basic level, you can always add power-ups and stuff like that later (just keep your framework open for additions).
Some reading advices:
http://games.greggma...ming_m_c__kids/ - An article on the development of an old NES platformer (M.C. Kids), topics like general gameplay, game-logic and collision checking (in-depth) are mentioned, a really good read!
http://lazyfoo.net/S...rials/index.php - If you choose SDL, read these!
There are also some (recent) topics about getting started in game programming here on the forums (developers corner), I recommend looking for them as they contain some more useful links, hints and advices
for example:
http://www.gp32x.de...ware-and-stuff/ and
http://www.gp32x.de...mers-out-there/
foxblock out