I work more with water myself. I spent a lot of time working with all the elements but I seem to best with water too. There is a lot you can do with water magick and there are several books involving working with the elements in general. I recommend looking into the following books as each one has some info on working with just water magick.
-Earth, Air, Fire & Water by Scott Cunningham
-Elemental Witch: Fire, Air, Water, Earth; Discover Your Natural Affinity by Tammy Sullivan
-Elemental Magick by DJ Conway
-The Way of Four: Working Magic with the Elements by Deborah Lipp
And here are some water only oriented books:
-Sea Magic: Connecting with the Ocean's Energy by Sandra Kynes
-Magickal Mermaids and Water Creatures: Invoke the Magick of the Waters by DJ Conway
-Water Magic: Healing Bath Recipes for the Body, Spirit, and Soul by Mary Muryn
-Enchantments: 200 Spells for Bath & Beauty Enhancement by Edain McCoy (Mostly things for the bath but it is water oriented)
-Ocean Oracle: What Seashells Reveal About Our True Nature by Michelle Hanson
Many of these books are available in kindle format if you are tight on money. Some libraries might have a couple of them, if not you can see if you library does a loan program with other libraries that might have them. Otherwise, amazon and used book stores are a good place.
Also the site http://www.mistresskalpanasrealm.com/ used to offer water magick based classes using some of the above books. However, this site isn't one to be taken lightly. Its free but much like taking college classes. Its hard but very rewarding. I've taken many classes on it and learned more than studying on my own with just a book.
One last thing. There are several non-water practices that are used by witches who favor working with water. Scrying and mirror magick due to the surfaces being similar to that of water. Moon magick because of the link to the tides. Knot magick because it was used in sea witchery as a method to tie up the winds for sailors. Seashells as a form of tools or spell ingredients and even divination. Drift wood is also popular with water witches to make divination systems out of like runes or ogham. The more you learn about water magick the more you will find links to other things that can be tied into the practice of it.
I hope this has been helpful. Good luck!