Introduction get started

Open excel and save your file into a separate folder.
excel will default and load 3 work sheets in the same file. To keep it manageable delete worksheet 2 and 3, then work in sheet 1 and save.
Generate new folder on your hard drive
Store all future related files in the same folder, as you progress your files will be linked in order to maintain the data flow and to have easy access ability and input.
You will be building a customized application within excel for your requirement

Forward Plan your requirements, NOT what you need now, include any likely items that you may need in the future for that section. if you are not sure leave extra cells just in case. Down side is, you will have to go back to square one to insert 12 months down the road and all links at that point would have to be reestablished.
YOU REALY DONT WANT TO GO THERE
List all your header items in order of your preference in separate cells horizontally.
STOCK ITEM / WHOLESALE COST / PROFIT % / RETAIL  etc.
It is best to layout in the order that it would happen
1 ITEM  2 COST OF ITEM
( you might want to insert supplier/supplier detail/invoice no.and so on)
3 PROFIT MARGIN  4 RETAIL COST ( variable ) 
5 ITEMS IN STOCK
( you might want to insert stock control levels and so on}

AT THE MOMENT KEEP IT SIMPLE AND MANAGABLE
Keep all data in a manageable size and vi sable on the screen if possible
rather than arrange the whole year, divide into weeks or months and separate into different departments. It is best to run on a weekly cycle to incorporate any event or delivery
( example ) Bar Stock Control ( SEPERATE FILES )
beers, wines, spirits, consumables etc
can all be separated to define cost, calculate % and running costs which flow into a year/month/week/ or even day to day summaries

ARRANGE YOUR PAGE

arrange your page to be structured in a way as to be easy to follow and navigate Keep the same order and colour format throughout.
its easier to follow and manage
Colour code sections to make easy identification as the data flows through different files and sheets, but always retain a format that is legible and clear on screen and printouts
No need to colour code each related cell the header alone would do.
Example the page you are viewing is designed to separate key factors with colour tagging to make it user friendly.
Make your file/s user friendly
As you are working on a file/s or section of a file you can always colour tag the section you are working on and remove when you have checked and finished the section you are building or editing.
You can put a temporary line around a cell/s or a block of cells to aid your editing process. Remove when finished, this will help you to be structured and organized when building multiple levels within your application
Always minimize the maintenance