Here's a great blog post by Liz, a first-time kayaker we had the fun of taking out at Chehalem Paddle Launch.
(excerpt) ...She fitted me with a lifejacket, paddle and kayak. There are 14-foot and 12-foot boats. I chose the shorter, more stable length. She gave me a thorough and informative safety rundown, carried my boat to the water and helped me launch. At the very moment Melissa warned me about the deep mud at the bank, I sunk in ankle deep. So watch out for that.