The general blue folder will have the note overprinted with a date. These folders AA01-AA22 are common. If by chance you have serials AA00 or AA23 then those notes are worth more if uncirculated.
The first series without the date had a problem with the varnish over the OVD. Those banknotes in uncirculated condition need to have the 3rd and 4th numbers in the serial being 93,94 or 96 only. The best serials are AB10 which is the first prefix and AB33 which is the last prefix.
The second series has no overprint either. The best serials are AB10 which is the first prefix and AB57 which is the very scarce last prefix. The Renniks R32 catalogue values the AB10 at $550 and the AB57 at $2150 in uncirculated condition.