You should try various ways and setting pies, as Peck said, i do all my pictures outside, i have a balcony here in Munich so it's not generally a problem if it rains either. Just try different ways and see what suits you and the camera best, i also use the highest resolution settings plus macro mode, it all works for me and get great results with a 5 year old Olympus 8mmp camera. P.s, the bigger the coin, the nearer to it you can take a picture, smaller coins need a bit of distance inbetween, i have'nt quite mastered copper bronze yet but am working on that, and lastly, always make sure there's a bit of land between the coin so you can crop and rotate if required