Hats off to you. It's a very good idea to keep a record of where they come from right from the start... people will find the first few and be able to tell you to within inches of where it was found but after you start finding a lot, from a number of different sites over a span of years..... good luck. Half of their value comes from knowing where they came from, then they are useful to scholars years or centuries down the road... There are many different ways you can keep a record, I will tell you what I do, and by no means is it the only or best way but I'm glad as all heck that I have!!
I bought an art pen that had acid free ink. I would mark it with a single number starting with 1 and then a slash mark followed by the year I found it. I keep an official record book with all my sites listed and what is found at each one each year. I name the site, and often times when recorded with the state this is the name that sticks as the official site name. I give a description of the site starting with what county, what township, what section, what quarter section, so on and so forth... then I also do a sketch of each artifact that comes from each site so that years down the road if the artifacts themselves become separated from the record book I will still "have" what was found.
Just as an example (section numbers and what not I'm just making up in this case for obvious reasons) one of my site descriptions in my record book would look like this:
The Dead Horse Creek Site Number 2
Adams County Wisconsin
Town of Big Flats
Section 13
NW 1/4 of the SE 1/4 of the SW 1/4 along the banks of the Dead Horse Creek on the farm currently farmed by the Smith Family.
Then I would have a sketch of each artifact found at the site with it's corresponding number, for instance (minus the sketches) I might have #12/98, #13/98, #23/98, #6/99, #24/00, #2/01, #3/01, #17/05, etc etc..... I use the ink to write the numbers like the above right on a very small and inconspicuous spot right on the artifact itself, usually on the "ugly" side so that when it's displayed the numbers aren't visible. Then I cover the ink with a clear coat of nail polish. The number will never wear off and if for some strange reason somebody down the line wouldn't care about the associated information that went with it, it would be easy to remove.