I came up with a system of my own that has been working well for a few years.
First, I made a spreadsheet with a list of sequential numbers. These are my Job ID #'s and I print about 200 at a time.
My work orders are designed in Word, so I do a mail merge and my work-orders are pre-printed with job #'s already on them, so there's no room for error as far as someone writing the wrong # on the work order or not putting a job # on it at all.
Next, I use the Avery Removable Labels (mini-address size, 80 to a page) with job numbers pre-printed on them in word. I print 4 of each number (so there are 20 rows of labels, 4 across ... each row contains 4 of the same #). It took a bit of manual work the first time I made them (couldn't find an easy way to merge with my excel file in each of the 4 columns) so I ended up typing up the first sheet manually ... 1000, 1001, 1002, up to 1019, then copy & paste to the other 3 columns. Now, whenever I need to print more labels, I use Word's "find & replace all" feature. In the example given above, I would find 100 and replace it with 102 and find 101 and replace it with 103. (yes, this omits the last number which doesn't need to change). So, 1000 becomes 1020, 1001 becomes 1021, 1019 becomes 1039. This really isn't as complicated as I've probably made it sound ... sorry about that!
I print TWO of each sheet of labels - one for the front office and one for the bench area, meaning we have 8 stickers available for every Job #. The set out front is used to tag everything as it comes in (laptop, AC adapter, recovery discs, flash drives, etc.). If we use up all 4 labels out front (rarely happens), we can go grab an extra label from the set in the back. The set in the back is primarily used for when we open a computer and start taking stuff apart. Every piece that comes out of the computer (hard drive, optical drive, etc.) must have a sticker attached to it immediately.
Best of all, since the labels are removable, we easily peel them off as we put stuff back together and no sticky residue is left behind.