A previous responder had a good basic list of clothes. Here's what I'd recommend:
Neoprene booties for sheltering your tender footsies
"Farmer John" Wetsuit (i.e sleeveless) It can be a shorty or a full-leg
Pair of board shorts
A form-fitting fleece pullover
A splash jacket or dry top
The above list will get you through just about any summer/early fall boating you might encounter. Obviously if the water's cold or if the seasons turn you'll need more layers. A pair of gloves might be nice, or a pair of splash pants or dry pants. Go with the advice about getting as much of this stuff used or from your Uncle Ralph as possible, because if you like kayaking you'll pretty quickly also discover what gear works best and know what to look for buying new.
The most important other piece of safety equipment is a buddy or two to have fun and explore with and to help fish you out of the drink when your roll misfires.
Best of luck and hope to see you on the river! (Of course, that probably won't happen unless you float the waters in CO)
-Τὸ χόβερκράφτ μου εἶναι γεμᾶτο χέλια!