There are literally thousands of programs for you to choose from. However, to get started you may want to choose something that you are familiar with. This product or service may not be the hottest thing on the current market or make you a millionaire, but you will come off more confident and sincere with something you know and believe in.
This will also help when it comes to creating your site. Something familiar will allow you to be personal and creative. Trying to create a site around something you know little about will soon become boring and tedious.
Working with something familiar will also give you the some experience in the program. You can always expand at a later time when you are more familiar with how things work.
Another good piece of advice is to watch the number of banners that you put up. A site full of banners will make the site look ugly and put off potential buyers. Carefully place your banners and use them to accent your site. Stuffing it full will not help.