2 more cents throws in:
If you use deferred shading (as described by LordJulian above)
DON'T! don't use deferred shading as described by me above, research it and use it as described by someone who actually used it; I only wanted to paint the available pictures.
Also, my advice is: use the forward shading technique, it's more forgiving. When that fails to provide the results you're looking for, add a post processing step and milk that into more and more complex filters. In no time you'll do the steps to prepare yourself for deferred shading and you won't even know it. Don't go full deferred until you are ready, deferred shading, while offering an elegant model that promises to solve lots of issues, presents lots of problems in itself. You'd have to be more controlled in the way you render your scene, with the different render targets and the way you pack/unpack information, etc. In one word, you'd have to be an obsessed management whore with your rendering pipeline(are we allowed to say whore in here? we should, it's the internets).
And, before you reach the "relevant shading data for that pixel" stage, you still have to first RENDER that data into the render targets; this is done, of course, with a custom shader that outputs all the needed values, which, later, will be interpreted by the super-shader. So, shader complexity is not really lower, it's just separated into multiple shaders, which, in itself, is a complex thing to do.
So, go gradually, and know that whatever you learn/experiment with "the classical way of applying shaders to models and basic lighting " will stay with you and will be relevant. Deferred shading is, after all, forward shading a full screen quad with some real-time generated textures .