Choosing a good hosting company is critical to your online success. There are hundreds if not thousands of hosting companies out there, so make sure you take your time choosing and do your research. Here are a few of the main points to look for when deciding:-
Reliability
If you are setting up a hobby or personal site then this may not be that important, if you are a large ecommerce site then this factor is critical. Visitors to your site have a very short attention span so if your site isn't available the first time they visit, they will not return. If the hosting company's servers are slow your visitors will just click through to your competition, never to be seen again. That's why its so important to ensure that your hosting company has the infrastructure and technology to keep your site online 99.9% of the time. Failure to do this could cost your business thousands of pounds a year in lost custom. Therefore its important that you take this into consideration when deciding on a host - don't just pick the cheapest - do your homework.
Capacity
If you have a large dynamic web site ensure that you have plenty of web space. Certain companies will charge heavily for extra space above what is allocated to the package you purchased. Also ensure that you allow plenty of room for future expansion of your site or sites. It may be difficult to upgrade your package in the future or there may be a limit to what your hosting company can provide. At the other end of scale don't waste money buying web space you will never use, you could use these savings for promoting your site instead.
Bandwidth
Be careful with this. Make sure that you have enough bandwidth to cover your current or future traffic requirements. Bandwidth can be used up very quickly if your site offers multimedia elements such as mp3 download or streaming video. Your hosting company will either shut down your site if you go over your limit or slap on a hefty charge for every MB you are over your limit. These costs can escalate very quickly, so the best rule of thumb is to ensure that you have enough bandwidth in the first place.
Application Support
Many people are now using dynamic elements such as databases or forums on their sites. Ensure that your host supports these dynamic elements as part of the package - not as paid extras. Look for things such as ASP, MySQL, PHP support. As a side note if you are using Microsoft FrontPage for building web sites, make sure your hosting company offer FrontPage extensions as standard, otherwise this will be another annoying additional charge.
Security
It is extremely important that your hosting company has adequate measures put in place for protecting your web site. They should have various firewall's put in place to prevent your site been hacked or suffer denial of service attacks (this is when your web site is inundated with requests, which causes your server to crash and your site to become disabled). They should also back up your data at regular intervals and allow you to make copies of everything contained on your server, for your own personal records.
Support
24/7 365 support should be standard with most hosting companies these days. However, make sure this support is not just email based. If your site goes down you will want to speak to a support engineer right away over the phone. Most of the decent hosting companies will provide this facility, and the better ones will even provide a toll-free number. Don't underestimate the benefits of this kind of service, there is nothing more panic inducing than having your web site offline over a weekend or holiday period and knowing that you are losing 1000s in lost sales.
Do Your Homework
Ask other webmasters on internet forums who they use. This is probably the best way to go as they will be using these hosting companies on a regular basis and will be able to give you their experience of using them. A good forum to visit to research your options is sitepoint.