Hi Michael,
Welcome to the worlds greatest hobby!
I am so glad I started an inventory early on. It has saved me many times from buying duplicates.
For what it's worth here is how I do it with excel
[TABLE="width: 2262"]
[TR]
[TD="class: xl24, width: 84, bgcolor: transparent"] [/TD]
[TD="class: xl29, width: 101, bgcolor: transparent"] [/TD]
[TD="class: xl29, width: 162, bgcolor: transparent"] [/TD]
[TD="class: xl32, width: 100, bgcolor: transparent"] [/TD]
[TD="class: xl29, width: 144, bgcolor: transparent"] [/TD]
[TD="class: xl30, width: 121, bgcolor: transparent"] [/TD]
[TD="class: xl31, width: 569, bgcolor: transparent"] [/TD]
[TD="class: xl34, width: 92, bgcolor: transparent"]Cost w/ Tax & Shipping[/TD]
[TD="class: xl29, width: 239, bgcolor: transparent"] [/TD]
[TD="class: xl24, width: 76, bgcolor: transparent"] [/TD]
[TD="class: xl28, width: 154, bgcolor: transparent, colspan: 2"]Greenberg's Price 13[/TD]
[TD="class: xl33, width: 357, bgcolor: transparent"] [/TD]
[TD="class: xl35, width: 815, bgcolor: transparent"]Notes, Updates, etc.[/TD]
[/TR]
[TR]
[TD="class: xl25, bgcolor: transparent"]Era[/TD]
[TD="class: xl25, bgcolor: transparent"]Gauge/Scale[/TD]
[TD="class: xl24, bgcolor: transparent"]Type[/TD]
[TD="class: xl26, bgcolor: transparent"]Date Ordered[/TD]
[TD="class: xl24, bgcolor: transparent"]Manufacturer[/TD]
[TD="class: xl25, bgcolor: transparent"]Manufacturers #[/TD]
[TD="class: xl24, bgcolor: transparent"]Description[/TD]
[TD="class: xl29, bgcolor: transparent"]Vendor[/TD]
[TD="class: xl25, bgcolor: transparent"]Condition[/TD]
[TD="class: xl27, bgcolor: transparent"]Exec[/TD]
[TD="class: xl28, bgcolor: transparent"]Mint[/TD]
[TD="class: xl29, bgcolor: transparent"]Includes[/TD]
[/TR]
[/TABLE]
I have revised it many times and now I make separate books for different types of equipment.
On Order - Sets & Packs - Locomotives - Rolling Stock - Holiday Cars - Accessories - Buildings - Vehicles - Track - Power & Control - Pre & Post War - Parts - HO - N - Inventory Sold
I am primarily a Lionel man but lately my HO is growing and I am thinking of breaking it down in other books like my Lionel
It's a lot of help to me and easy to keep up with if you do it as soon as you buy, upgrade or modify something. I like having the On Order Book because sometimes I forget what I ordered and when it arrives I just cut and paste it into the correct book. Once you have it started it only takes a few minutes to keep up with it or to modify it to meet your changing needs.
I hope that helps.
have fun!