My advice, go to a few different LBS's, try on every shoe they have from different manufacturers. Don't be afraid to try on size up and down. The different manufacturers use different lasts to build the shoes, so a size 45 from SIDI, may not fit the same as a 45 from Shimano. And you may find that some brands just feel better than others, they fit your foot better. Take your time, your feet are an important contact point on your bike, getting it wrong will hurt, getting it right will make your riding more enjoyable.