I was fascinated with this technique when I was starting out experimenting with macro and din’t have a macro lens. This a great technique to get some nice shots you can’t normally and to have some fun.
Here are a couple of tips I learnt:
>Using a fast prime as the base lens and and a wide zoom reversed works really well. ( I used a canon 50mm 1.8 with a kit 18-55mm for the shots in the links below). You can couple most lens brands as long as their aperture is either manual or widest at idle (most canon EF and EF-S lenses are widest at idle. Many nikon lenses are narrowest at idle but it might be possible to hold the aperture open manually).
> Try out different apertures, zoom levels and combinations of lenses. It is possible to use a single lens but beware of dust entering the sensor if not using an adapter.
> When you reverse a zoom lens, remember that zoom value reverses as well (for example in an 18-55mm the lens will be zoomed in at 18mm and zoomed out at 55mm).
>Using a tripod and a coupler ring (to attach two lenses) will save you frustration. Check the filter size for your lenses to get the right coupler ring.
>Focusing is done by physically moving the camera closer or away from the object. If possible, it might be easier to and move the object instead for perfect focus, specially if you’re using a tripod.
> Be careful of lens vignetting or use it creatively.
> Depth of field is usually very very shallow with this technique. It might be better to have you subject on a plane level to the camera if you want most of it in focus (You could try shooting something like a coin from different angles to understand this).
Here are some pics I shot using the technique, using a canon 50mm 1.8 (on camera) coupled with a kit 18-55mm lens with a canon 550D
hope that helps,