First Trip
So you just impulse-bought a new kayak at Walmart. Now what?
Don't take it someplace hairy for your first trip. Pick a place that is easy - shallow enough to stand up, no tides, no wind, no waves, no motorboats, no currents, no cold. Find some nice inland lake, I have quite a few of them listed. Learn how to get in and out of the boat, how to paddle, etc. Get a feel for things before you head out into the big water.
Also, figure out how to secure the boat for transport. The pool noodles and twine that you used to take the boat home from the store on the roof of the car are not suitable for the highway. Get whatever racks and tie-downs you need and figure out how to set them up properly. I always use a minimum of two completely independent tie-downs, even for the most local of trips. On the highway, double that.