Who, what, when, where, why, and how
The first step in planning a new database is to write down its purpose. In this case, you need to enter and manage your company's asset data. But don't stop there. Ask yourself who will use the database and how they'll use it. For example, the technician who fixes a defective machine has different information needs than the accountant who tracks costs. Make sure your purpose statement addresses all of those different needs and uses.
Keep your purpose statement handy and refer to it as you design your tables. And don't try to make the statement perfect, you can always change it, and you probably will.