Because of our chemistries, it is hard because the same cologne, or perfume for that matter, can smell one way on one person and not so nice on the next. If looking for something new, I would suggest as Nicks Nose mentions going by a counter, scenting, and then trying some to find what appeals to you. The sales personnel can be very helpful sometimes if you tell them what you have worn in the past and liked, and then to make some suggestions too. A trick though is to smell your sleeve or take a small bag of coffee beans/grounds to smell in between scents to clear your nose and to not to confuse them or get overwhelmed with all the smells. They may have samples to take home of some and to try as well before you actually decide if you are not sure about something, or just commit to a smaller bottle that you are interested in until you know for sure.
Happy sniffing!