I've got a Prowler 13, ver stable yak. I actually fish Side Saddle in it sometimes when the water is calm. PFD is a Must....I took mine out on the ponds for the 1st 3-4 times to get used to it and after that hit the ocean.
Practice self rescues in it. Here is a link to a page for self rescues in the Ocean Kayaks.
How To Re-enter a Kayak - Kayaking Basics - Ocean Kayak
1st time I tried it wasn't pretty and you don't want to find that out when you are on the ocean...after a couple of tries I got the hang of it and got back in pretty quickly.
Be mindful of Wind Conditions before you go out....that can cause you problems, paddling against a strong wind can be a miserable experience.
If you are going out at night get a stern light and a Flag....that way the boaters that are out there have a better chance to see you.