Nowadays kayaks are commodity items like bicycles, and it is easy to buy a thing that you have no experience in using. So here are some pointers for beginners.
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A New Jersey "Blue Hole" is a sand quarry that has filled with water from the aquifer below. These are very dangerous places. This is because, although the visible part may look like a Caribbean beach, the underwater sides of the quarry are steep and unstable, and merely walking near the edge can cause a collapse into the hole. The water is deep and cold, and the victim is quickly overcome by shock and hypothermia and drowns.
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When dealing with a non-negligible wind or current situation, you'll probably think it will be fun to go with it and have a good ride. That's fine if you are making a one-way trip, but if you are making a round-trip back to your starting point, this is a very bad idea. The boost can carry you much further than you realize, and then you'll have to fight against it all the way back. Your fun day out can turn into a miserable slog.
It's much better and safer to head into the current on the outbound leg, and let it carry you home on the return.
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A weir or low-head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of lakes, ponds, and reservoirs. There are many weir designs, but commonly water flows freely over the top of the weir crest before cascading down to a lower level.
Even though the water around weirs can often appear relatively calm, they can be extremely dangerous places to boat, swim, or wade, as the circulation patterns on the downstream side - typically called a hydraulic jump - can submerge a person indefinitely. This phenomenon is so well known to canoeists, kayakers, and others who spend time on rivers that they even have a rueful name for weirs: "drowning machines".
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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.
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Do you have a cell phone? You'll probably want to bring it along, and it probably has GPS. This can be very handy out in the wilds of New Jersey. Even if your phone doesn't have GPS, it can triangulate off nearby cell towers and give you a general location.
The cheapest way to use your GPS is to install Google Earth on your phone. That will give you a bird's-eye view of where you are, and a compass. Pretty basic, but it's free. If you want more, you can get a mapping app. I use OsmAnd on Android. The advantage of this is that it can record your trip. Later, you can see how far you went, etc. If you're like me, you'll forget to turn it off and record your drive home too.
Like most phone apps, OsmAnd's user interface is like some sort of puzzle game. The trip recording function is actually a plugin. Figure it all out before you go out, and you won't end up wanting to throw your phone in the water. I've actually used OsmAnd for years, but the developer keeps making unnecessary changes, so every few months you get to re-learn it.
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Should I get a paddleboard or a kayak?
Get a kayak. You can do a lot more with a kayak. I honestly don't see the point of a paddleboard. If you think you'll look cool like a surfer, trust me, you won't.
Should I get a kayak or a canoe?
For one person, I think a kayak is better, but I'd rather have a canoe than a two-place kayak. Then again, I'd rather have two kayaks than a canoe.
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Kayaks are pretty seaworthy, sit-on-tops are just about unsinkable. That said, dealing with anything more than a 1-foot chop in a flat-bottomed lake boat is really no fun. If you find yourself caught out in rough water, try to keep the bow or stern pointed into the waves, or within 30 degrees of perpendicular, even if you have to take a roundabout course. Do not run parallel to the waves.
Boat wakes are also a threat. Most boats give no thought to anyone else, at least not anyone smaller than them, and will plow by without even looking at you. Always watch out for boat wakes, and turn into them like waves. When dealing with motorboats and jet-skis, I just assume they are drunk and not paying attention to anything. It hasn't failed me yet.
Crossing a boat channel is like crossing the highway: look both ways, wait for a good time, and do it as fast as you can. You do not have right-of-way. Unlike an automobile, a boat doesn't have brakes, and if you do something stupid, it will run right over you.
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