Right so your all ready to go.. you point your camera at the water and.. what DO you focus on?
The drops come too quickly to see clearly and one bit of water looks pretty much like another.
What I do is set the drops going and then lie a bread knife across where the drops hit the water. (Why a bread knife?.. it has a nice serrated edge thats easy to focus on). If your doing single drops then have the edge that your focusing on JUST in front of where the drops are landing. If you are doing impact splashes that you want to go out then move it so that you are focusing between 0.5cm and 1cm in front of where the drops land.
SET TO MANUAL FOCUS!! (I always focus up, then hit the button and it tries to autofocus and I have to go back to focusing again! :)
This is where having live-view and an option to magnify the screen comes in REALLY handy!
Other stuff I have used.. Piece of string across where I want to focus, pipe cleaner (really fuzzy works very well!) you can use pretty much anything.
Now you have to see what you want to do to make the stuff stand out.. I'll go into this in more detail at a later date but here's some ideas.
Plain water does not look like much, no contrast between it and the background and it does not reflect light it refracts whatever is behind it.
Put a background behind the drop, colourful, stripy pictures, a nice flower, anything can be a background, all give different effects.
Put some clear gel plastic infront of your flash and it will turn everything that colour. I've used a red plastic beaker before with some nice effects. 2 flashes with different colours can give some amazing looks. (I only have one flash at the moment, have experimented with covering half with different colours.. kinda worked)
These can work really well.. Different colours in the bowl of water and in the droplets can make some great effects. Can be messy!!
Also once the two colours start to mix you can either end up with non-photogenic sludge or something quite unusual.. never sure what you will get.
Experiment.. try.. see what different colours you can get..