started off in macro using close up lenses- stack all of them on top of each other and you're in macro/flare heaven- horrible things
then started using the kit lens reversed, using my finger to close down the apperture- works really well and I still use this technique today
recently shot this at 28mm reversed
bought a 28mm macro lens which is more for extreme perspective shots than true macto
and recently bought a kenko 2x macro teleconverter and a 50mm lens- works wonderfully as gives me 2 lenses in one- works great with the kit lens at 18mm or the 28mm macro (you can focus so close than things touch the front element)
havent tried doubling up a reversed lens but i'm having great results from the teleconverter- and it cost me next to nothing compared to something like the tamron 90mm macro
to the OP, the reason you're seeing black through the viewfinder is the lens is closed down- I think nikon lenses work the same as pentax where there is a lever at the back which controls apperture- either push this open with your finger or just twist the apperture ring to f8 or whatever you're desired aperture is, this will make focussing tricky though as the viewfinder will be very dark- so I actually find it easier to use the finger method and then close down to take the photo
Rollo was that shot using a ring flash? I can image you'd have to get closer to the insect than i'd like