Good morning SRH! I echo what everyone here has said. They're wise- do what they say. On top of that, wear a hat, a neckerchief, bring water and a snack, bring a good DEET insect repelant- the mosquitos are BAD and will drive you crazy before you can focus on the ground! Also- look for the shape (although many tools are natural-looking, many points and mortar and pestle (mano and grinding stone) are just too trianguar, too round, too oval, etc to be natural. There are exceptions to this certainly, but, sometimes it helps-- when all you see is chunks of rock- then to spy a triangle with a 'bright edge'-- it'll catch your eye. Watch for that.) Also look for a 'bright' surface (flaking on points tends to reflect well)-- and color. Many times, 'different' or non-native stone was used to make nice points. Keep your eyes open for something that doesn't 'fit' (while humming the Sesame Street song, 'One of these things is not llike the other one...')
If you're in the woods (a woodsy creek), watch for ticks- I always wear long pants tucked into boots. Protects me from poison ivy too, which I have a terrible time with...
Have a great time! And remember, if it's an old place, you may also find an old dump- with cool things like bottles, buttons, odd iron things and curiosities. If I feel I'm getting skunked for one thing, I often change my 'goal' and go for what's there. I have a friend who basically puts her blinders on and goes for the points only. When there are none to be found, she goes home upset and defeated-- while I may come away with a cool bottle or crock, an old 'Tootsie Toy' car or a button- and be walking on air for having found something.
Good luck, welcome, and as always, HAPPY HUNTING!!!