Thats bootifull. Wish I was that ambitious.It all depends on your desired end product.
Just clean them? Original Bike Spirits and some soft rags.
Remove oxidation from the exposed edges where there's no engine paint? Use your favorite aluminum polish (White Diamond is a favorite around here)
But if you're looking for something amazing - you'll actually need to sand down the machine marks with increasing grits of sand paper and the polish them up with a really good aluminum polish.
If you have a black engine casing (spec 2 or 3) then you'll also want to clean up the black between the fins. I used Original Bike Spirits and Q-Tips and a rag wrapped over a wood shim to help scrub yet go quickly.