My website is hosted on a Shared web hosting account but it has many problems. Why Shared Web Hosting Sucks ?
Because anyone on your shared server can crash your website and cause it problems!Then you have to wait for your hosting company to fix the problem and ban the offending site or give them another shot. Plus this can happen at anytime as any site can get dugg or slashdotted and cause all the people on one server problems.
Shared Web Hosting has many disadvantages so A VPS is a good start, it basically has software that splits up a server into individual emulated servers. In this environment the other sites are separate and can't affect you.
A dedicated server is also an option as then you have an entire server for your site. If you can't afford either of those options just finding more expensive shared hosting that doesn't oversell as much will help. There are lots of shared hosts that are for programmers and they don't oversell as much.