When it comes to decorating a home office, my first recommendation would be to choose a lively paint color that is sure to help boost your creativity. If there's one space in your home that can carry a bright paint color (think along the lines of orange, green, even a canary yellow), it's the office. You want to walk into this space feeling energized every time and this is one of the easiest ways to accomplish this.
And of course you might think of displaying your diplomas, awards, and the like, but also consider showcasing pieces of art that speak to you personally or propping special family photos up on your bookshelves for an extra dose of inspiration. Elements that can keep you calm while you try to meet deadlines and fulfill work obligations are key.
Another way to pick up the energy in the space is through fun desk accessories and supplies. There are tons of affordable outlets (one of my favorites is See Jane Work) that offer more stylish options way beyond the standard black stapler or silver metal letter tray, for instance. Get creative with your accessories. You'd be surprised how an element this small can amp up your creativity level.
Get to work, and happy decorating!