Security. Security should come first, because it is very easy for some unscrupulous hackers to break into an unsecured server and view all of the information on it. You really don’t want that to happen, not to you, and especially not to your clients or site users. That’s why you have to make sure the hosting company provides the best security measures possible, keeps their software updated and removes any infiltrations or at least notifies you about them. You can find all of that out by reading their Terms of Service or contacting them directly (most of them will be happy to tell you what they do to secure your data).
Reliability. The hosting package you choose must also be reliable, and not shut down every other day or so. A bit of down time is practically unavoidable on shared hosting because of hardware upgrades, temporary overloads and software issues, but you have to make sure that the hosting company does everything possible to reduce that time to a minimum.
Performance. The performance of a shared hosting package is directly related to the performance of the physical machine your account is on. If the hosting company uses old and weak computers as servers, that’s a very bad sign, but it can be difficult to find out what exactly they use, in which case an external tool like LoadImpact.com can help you.
Features. The features that come with your hosting package are very important, because if it lacks something, you won’t be able to install the software you need and you also won’t be able to do anything about it, other than moving to another company. For example, a lot of hosting packages come without IonCube or Zend Optimizer, 2 popular encoding/decoding tools without which a lot of scripts can’t run. Even worse, there are hosts that don’t even give you a MySQL server, so you basically can’t run any modern software on their hosting packages.
Price. I put the price factor last because compared to the above ones, it is really not that important. Thanks to there being hundreds of competing companies, hosting is really cheap anyway nowadays. But you still have to choose something that suits you, because it’s really not necessary to pay $20 per month for a package that costs only $10 at a competing company, all other things being equal.
By paying attention to all of the factors listed above and choosing what you really need, you will definitely be able to weed out the bad providers and get a good, reliable shared hosting package that will serve you well for as long as you keep it.