Before trying to build a data warehouse, I would definitely recommend reading Ralph Kimball's book. I have a really old copy of The Data Warehouse Toolkit. There are newer versions, but the thing to take away from the book is what a properly structured star schema looks like. Once you have that, you can go on and build cubes etc and your structure won't really change. Yes, you could add more dimension (lookup) tables... But I would start by getting a solid understanding of the star schema and how to implement it right.