One of the most important thngs to think about in your new office is the design. The design that you come up with should be conducive to the type of work you are doing and the type of business you are trying to build and run. If your brother is an accountant, but you run a video game development company, your offices will more than likely tend to be laid back, with more casual furniture and art on the walls, like framed box art or comic book covers. It is going to be significantly different from the office environmentof your brother the accountant.
Do spend some time and evaluate what your needs are, then simply lay out your office design accordingly. The best thing you can do is come up with an office environment design that mirrors the type of work you will be doing. This will allow you and other workers to be more comfortable and feel that they can do their jobs in this type of atmosphere.