With the internet and email, don't worry about having to visit or even talk to travel agents. Most everything is done via email now anyway. I have a client in South Africa that has been with me for 10 years and I've talked to him one time. He was visiting his daughter in the U.S. and just had to give me a call so we could talk. Strange hearing his great accent after all these years. Same with my Australian clients - have not yet had the opportunity to hear their wonderful accent I love so well!
But definitely look for one who is reputable, listens to your questions, is responsive, and helps you find the perfect cruise for your specific situation. If they start 'recommending' things, run the other way because usually when they're recommending it's not necessary in your best interest. Their job is to give you as much information as you can handle so you can make an informed decision.
Hope you find what you're looking for!