It should be obvious that sturdy tripod has to be used to avoid any shake between the photos. Besides you probably want to set your camera to manual mode (also focusing should be done manually in many cases). This will ensure that your photos won't change colours/white balance/sharpness due to changing lighting conditions (eg. clouds can appear at some moment and that would cause camera light meter to behave differently than it was at the beginning when the sun was shining) or subject movement.
Besides I used remote shooting from my laptop (using Canon software and having my DSLR connected via USB). This is for three reasons:
- I'm thus sure that interval won't change between the photos - I mean when shooting manually I would have to use timer and for sure I will shoot some photos too early or too late,
- With hundreds of photos I would soon run out of memory (I shoot mostly hi-res RAWs). Remote shooting enables you to save photos directly to your hard drive,
- It's more convenient. With everything set up I was able to do something completely different like surfing the net.
Below you can see the example time lapse I took today:
These 16 seconds are fast-forward of two hours. The subject is Selaginella lepidophylla - amazing desert plant. Which can survive many months without a single drop of water! I know the example is not perfect but for me it was just the first attempt. I had to move both the subject and the tripod because some shadows appeared at some time which made everything too dark.
The most impressive piece of work I've ever heard of was time lapse of two years of forest life! That's really amazing and what a sacrifice! Around the web you can also find some wonderful time lapse combined with light graffiti technique.