GPS systems for outdoor gardens

I want a very accurate GPS system in which I can mark and save in it - where certain places are. I know I have to be very careful with shit like that so if there are any tips about how to safely use them in this type of situation, too, that would be awesome. Just don't be a dick about it. I want to be able to save in my GPS where certain places in the woods are. I won't save the exact location of my garden but maybe the beginning of my path towards my garden you know?

Please let me know any tips on using them - AND - which handheld GPS systems are THE BEST.

Thanks.