I've been taking 1:1 shots (which is VERY difficult without a macro focusing rail)
This comes with practice. A good technique is setting the magnification first, then rock back and forth to get the plane of focus onto the desired point.

There are two main points of consideration when acquiring macro gear:
1. Required magnification: this is usually 1x magnification
2. Working distance
There are several “routes†into higher magnification, these includes:
- Extension tubes: These are basically just a metal tube with electronic connections. The purpose is to increase the distance between the focal point and the sensor/film. This allows for closer focusing, however you lose the ability to focus to infinity. Extension tubes do not contain any optical elements, and thus theoretically do not degrade image quality. The best value for money tubes are the Kenko set of three. They are manufactured for every major camera mount that exist.
- Diopters: Diopters are essentially high quality magnifying glasses. Both Nikon and Canon offers these. The multi-element ones are much much better, but with corresponding prices. Nikons are called the 3T, 6T etc and Canon's the 500D and 250D. Testing gives a slight edge to the Canon 500D, but the Nikon's are cheaper. Not brand specific. If you do go this route, buy the 77mm one and get a 77->Xmm step-down adapter, this way it can be used all future lenses too and thus protecting your investment. Nikon have recently discontinued their T series of diopters.
- Reverse mounting: These adapters allow you to mount your camera lens in the reverse direction. This effectively turn your lens into a very high quality and magnification diopter. These adapters are cheap and easily found on Ebay.
- Dedicated macro lens: The only lens that fits the bill would be the Canon MP-E65. While this sounds great, the 65 isn't for the faint hearted. It is difficult to shoot with but can produce excellent results with practice.
- Teleconverters: These are specially designed "lens". However, you will find that Canon/Nikon TC's are not compatible with third party lenses. In addition, Canon and Nikon TC+lens combo are specially designed to maximise performance, i.e. some Canon lenses have a hole at the back for the TC to insert into. In fact, compatibility with manufacturer's TC is one of the strong points going for Canon/Nikon macro lenses over 3rd party offerings.
With these many choices all providing extra “macro†capabilities, which one is suitable for you? It depends on your purpose. Here's some pro and cons for each of the above:
Extension tubes are cheap, but you lose quite a bit of light. A 25mm ext tube will cut the light by about 2 stops (need 4x longer exposure to achieve the same exposure). Extension tubes can be used on longer lenses to reduce working distance. i.e. the 300mm lens + extension tubes is a favourite for shooting butterflies. You lose infinity focus with ext tubes.
Diopters are cheap, and high quality diopters give good optical result. They work on all lenses so long as the filter ring fits (hence getting the biggest one protects your investment). Examples of diopters include Canon’s 500D and Nikon’s 3T. You also lose infinity focus with this.
Reverse mounting a lens gives very high magnification but the working distance is very bad. Personally I would recommend this only to more seasoned macro shooters. It's not all that useful for everyday macro shooting since it gives very high magnification. In terms of aquarium photography, this technique can only be used to photograph subjects close to the glass due to the poor working distance. No infinity focus, but is very economical. The adapter rings can be had on Ebay for next to nothing. This approach stands the highest chance of being approved by the CFO.
Some example of high magnification:
Canon EF MP-E65:
Stacked extension tube:
