I agree with pix3m u should just go for standard rpg perspective (follow cyan's advice) and none of that Zelda stuff.
otherwise its going to do ur head in trying to add diffeent things into a scene.
i think u should start put by roughing a scene (mockup screen) without getting too caught up in particular details.
e.g fence, yard, car, bushes, path, grass etc.
just block them in basic shades to get the contrast and lighting, then go over it all with a rough detail fill, add in shadows etc.