The two most important things were given by Plumberdv, "DO IT NOW", and 300Bucks, "BACK UP, BACK UP". I use a separate Excel workbook for each major collecting area: 110s, 102s, 300 Series, Miscellaneous Buck knives, Gerber 1960s-1970s fixed blades and Miscellaneous Knives. You can make a column for each thing you feel is important. I use a Mac with the Time Machine feature that automatically backs up everything on the computer every hour onto a external hard drive. I put the photos in separate photo albums, not on the Excel spreadsheets. The first thing I do when I get a knife is to enter the data on the spreadsheet. That's a lot easier than waiting until you have a bunch of knives to enter.
The most disturbing thing is that I have three columns for cost: price, shipping and total cost. At the bottom of each column, the total spent for all knives on the spreadsheet is generated automatically. That's why it's better to have separate spreadsheets for different models; you don't see the total cost for your collection unless you add the totals from each sheet.
Bert