Kayaking is one of my first outdoor passions. I'll throw a few tips in this thread for others to learn from.
On transportation:
Twist tie down straps to prevent the "machine gun" rattling at speed while driving.
Avoid excessive pressure on a rotomolded boat in the Summer when tying it down. The heat plus pressure will cause the boat to deform.
On safety:
Carry your keys in your PFD, not your boat. During a nasty swim, you could lose your boat but hopefully not your PFD that is on you.
Stay hydrated. Especially with whitewater kayaking, you won't know you're sweating because of all the splash. Replenish your fluids!
When paddling in cold water, insulate the bottom of your boat with closed foam. Even though you may have paddling pants or wetsuit bottoms on, conduction cold is a killer.
Carry a knife and practice using it in wet conditions. Lanyard use is a personal preference but I hate them. I'd rather not have a swinging piece of steel out there to cut me.
On paddling technique:
Make sure to push and pull with all of your strokes and incorporate your core muscles. Your core has larger muscles than your arms. Incorporate these to paddle with less fatigue. Twist at the waist whenever you can.
Make sure to sit upright and lean slightly forward. Leaning back in your boat is only acceptable during breaks and it doesn't allow for good control of your craft.
If your hands are getting too cold while grabbing your paddle, you're grasping it too hard. Open your hand on the off side while paddling but retain a grip on the paddle with your thumb hooked around the shaft. This will prevent your hands from cramping and it will keep them warm.
On post paddling:
Get a large bag you can step in to change out of your clothes in. This will keep your clothes from getting dirt and debris all over them plus it will keep your feet off of the gravel which is always a pain in the butt to remove before putting your socks back on.
Start your car (if you are a drop and play paddler) and turn the heat on immediately. Even though it is 90 degrees outside, you'll be happy you did!
I'll post more soon. Hope these help.