Choosing a good host is one of the most important decisions you will make about your online business. A poor host provides constant distractions, downtime, or content loss. Perhaps the most critical component of a good shared hosting company is their support. Test a prospective host; send them an e-mail question, or even call. If you do not get a response in less than 12 hours for e-mail, or cannot get through to a support person on the phone, look elsewhere. You will have technical support issues sooner or later, and every minute you wait for help is a minute you are losing money.
Space and bandwidth are important in your web host decision process. If you are doing a small e-commerce site, space is a minor issue unless you are hosting a large amount of video or pictures. New websites with little traffic also require little bandwidth. However, to make money, you will need some traffic, so make sure there is room to grow. Also, decide if you are hosting one domain or many. Hosting solutions often offer packages to support a single domain, or a single domain with add on domains. If you are likely to host additional websites, look for a plan that allows add on domains.
You need to consider what additional hosting requirements you need. If you are running an e-commerce store, you will need PHP and MySQL as part of your hosting package. Anything beyond a simple html pages require those tools, such as WordPress or Joomla. If you are interested in great web tools such as WordPress, but lack any UNIX experience, look for a program called Fantastico as part of the package. Fantastico makes installation of CMS systems simple.
Finally consider price. Basic shared hosting is inexpensive. At this point, you likely have no need of dedicated or shared servers, so stick with the inexpensive plans that meet your above requirements.