You’ve already started; doing your research is key. Have a look at architects’ websites and give them a call to find out more or arrange an initial meeting. Most architects will meet to discuss your aspirations for free. If you want anything more detailed or any design work you should expect to pay a small fee.
Once you have narrowed down your options and got comparable fee proposals (make sure that they are all quoting for the same levels of service and deliverables to get a real comparison) you need to make a decision. Lots of factors will influence this. Cost will of course be important, but so will design quality, approach, personality and confidence. Getting building work done can be stressful, so you will want someone to guide you through it that you can trust and engage with, and whom you feel will be honest and straightforward with you.