I would suggest searching "kitchen work triangle" to read a bit about placement ideas.

start with a floor plan on graph paper and gather the dimensions of the wall, doorways, window locations. learn the traffic patterns that people will use to avoid creating obstructions or awkward walk arounds. Research the needed distance between counter and island ( Most common mistake is "thinking" there is enough room for an island- because I want an island ) If this is an existing space measure it (twice) document the location of all electrical, all plumbing, all existing light fixtures, all doors and windows.

that's the start. those friendly associates at Home depot or Lowes can be a wealth of knowledge for understanding appliance size and locations in the space.

Hire a KD.

I agree with ellie that the kitchen work triangle is the best layout. Since you'll have an L shaped kitchen with an island, you can put your sink or stove or cooktop in the island to achieve the triangle.

VP Interiors 2010 · More Info

myself, i prefer the cooktop on the island, as it tends to be clean all day except during dinner prep, where sinks are 24/7 mess magnets.