a simple bath salts recipe I learned as a kid is this:
rock salt (the big grained stuff, can be found in small bags, often
used in the winter to salt driveways, etc.
one drop food coloring,
one drop fave perfume.
Adjust each of these to taste, but remember that the perfume mixes
very well, and can easily become to strong. the brighter the color
you want, teh more food coloring.
hope this helps.