i was going through my ones today that had a 5 digit serial number. starts 0004. it's not a star note. is it something that should still be set aside? advice appreciated
Up to you. If you like it, keep it - it's just a buck. Selling it for a premium is another thing, however. Unless it's uncirculated, from an older series, and/or a rare district, you will not get much over face value.
Most collector's view a "low serial number" as starting with at least 5 zeros. So, L00000999A and less would be a low serial. If you like the note, then I say keep it...but it doesn't have much collector value with that serial. Now, eBay auctions will call that a low serial...but to most collectors its not.
Serious collectors see a low serial as having 5 leading zeros. Some will even got to 4. On eBay, and only on eBay, even 1 leading zero is considered a low serial, and there are some bidiots that will eat those up.
For notes with three leading zeroes, I like to check to see if they are valid USPS zipcodes. If you can find the right person, you might get a few bucks. For example: I would love to have a serial number 00044647.
I say 4 leading zeroes only because I hardly ever find any in straps. Now if I found 4 leading 0's in straps all the time, that would be a different story. IMO, 3 leading 0's is not low, but as others said, if you like it, keep it; It's $1.