Creating EDRMS (Electronic Document and Records Manage Systems) in SharePoint is far to large and complex a subject to cover in a stack exchange question. There are entire consultancy companies that specialise in this kind of development.
I have built several such systems and am currently working on one for a county police force in the UK.
I can give you a few pointers:
- You need to clearly capture the requirements of the people who will be using the system. look at how they use the current system (even if it is a filing cabinet under someones desk) and how you can improve on that system.
- Do as much as you can with out of the box SharePoint functionality as this will make it easier to support the system you build. Custom code requires more expertise to administrate and maintain.
- Make maximum use of meta-data and content types. use the term-store to store these centrally and publish them across your deployment rather than recreating everything for each new site collection. Managed metadata is your friend when automating document management and record retention.
- For documents like how-to and best practice docs that are frequently changed, An enterprise Wiki can be a good alternative to more document libraries. they save space and can be easily editted on the fly by you service desk personel.
- make use of document templates to standardise information and help with automatically populating metadata fields when uploading documents. Many users won't have the training to do this job so an automated process is your friend.
I hope all this helps, As I say it is a very big subject. If you would like more detailed help with this then feel free to email me at email@example.com and we may be able to work out some consultancy hours.