To find a good designer
There are a number of designers out there, and some are versatile and can do a number of different designs. Some specialise in small areas and are exception, some are diverse, and lets face are a master of aspects of design. Looking at concepts and developmental work of a designer can give you some good insight into what look you want.
Past work in a portfolio can give you an idea if the designer specialises in certain areas that you are looking for. Sometimes a portfolio may not showcase what you want but the designer’s ability might allow him to go in any direction. Always believe in your designer, as some of them know what looks good, its sometimes better to listen to there ideas, as they have perceived the outcome.