The thing I love most about accessories is you can be bold and adventurous with them. You don't have to be too picky with the accessories you choose... just be creative.
Choose items that are different sizes and shapes but complement each other. For example and group of vases, all glass but different heights and widths. Grouped together with the small ones in the foreground and the large ones at the rear look well planned out.
Put beautiful bright flowers in them. Blue Hydrangeas in one, pink Roses in another and white Peonies in the third. This will show off your arrangement talents!
Then with that add a couple colourful ornaments coordinating with the colours of the flowers, you will surprise yourself!