agreed. also, potentially, for a 2D game, creating a level editor might be a learning experience or help give ideas for how to structure the game proper.
I don't know what type of 2D game you're creating, but for level design, I'd recommend creating a level editor, if you haven't already. First you need a clear definition and a list of what your game's levels will contain, then create your tool to save level data defining where walls, doors, enemy respawn points, whatever, into a scripting file like .xml or a custom format. Using your own level editor would make your life much easier. This way, you can put the relevant data in the right places upon load time.
a few questions to try to answer in advance:
does it use tiles or polygons? what sorts of things can go on in the world? will it be side-view, top-down, or isometric? how will things like enemies spawn? ...