Reliability and speed of access
Not only should the web hosting company be reliable and fast, it should guarantee its uptime (the time when it is functional). Look for a minimum uptime of 99%. In fact, even 99% is actually too low - it really should be 99.3% or higher. The host should provide some sort of refund (eg prorated refund or discount) if it falls below that figure. Note though that guarantees are often hard to enforce from your end - the host usually requires all sorts of documentation. However, without that guarantee, the web host will have little incentive to ensure that its servers are running all the time.
Data Transfer (Traffic/Bandwidth)
Data transfer (sometimes loosely referred to as “traffic” or “bandwidth”) is the amount of bytes transferred from your site to visitors when they browse your site.
Don’t believe any commercial web host that advertises “unlimited bandwidth”. The host has to pay for the bandwidth, and if you consume a lot of it, they will not silently bear your costs. Many high bandwidth websites have found this out the hard way when they suddenly receive an exhorbitant bill for having “exceeded” the “unlimited bandwidth”. Always look for details on how much traffic the package allows. I personally always stay clear of any host that advertises “unlimited transfer”, even if the exact amount is specified somewhere else (sometimes buried in their policy statements). Usually you will find that they redefine “unlimited” to be limited in some way.
To give you a rough idea of the typical traffic requirements of a website, most new sites that are not software archives or the like use less than 1GB of bandwidth per month. Your traffic requirements will grow over time, as your site becomes more well-known (and well-linked).
Disk space
For the same reason as bandwidth, watch out also for those “unlimited disk space” schemes. Most sites need less than 5MB of web space, so even if you are provided with a host that tempts you with 200MB or 500MB (or “unlimited space”), be aware that you are unlikely to use that space, so don’t let the 500MB space be too big a factor in your consideration when comparing with other web hosts. The hosting company is also aware of that, which is why they feel free to offer you that as a means of enticing you to host there. As a rough gauge, thefreecountry.com, which had about 150 pages when this article was first written, used less than 5MB for its pages and associated files.
Email, Autoresponders, POP3, Mail Forwarding
If you have your own site, you would probably want to have email addresses at your own domain, like sales@yourdomain.com, etc. Does the host provide this with the package? Does it allow you to have a catch-all email account that allows anyname@yourdomain.com to wind up being routed to you? Can you set an email address to automatically reply to the sender with a preset message (called an autoresponder)? Can you retrieve your mail with your email software? Can it be automatically forwarded to your current email address?
Control Panel
This is called various names by different hosts, but essentially, they all allow you to manage different aspects of your web account yourself. Typically, and at the very minimum, it should allow you to do things like add, delete, and manage your email addresses, and change passwords for your account. I would not go for a host where I have to go through their technical support each time I want to change a password or add/delete an email account. Such chores are common maintenance chores that every webmaster performs time and time again, and it would be a great hassle if you had to wait for their technical support to make the changes for you.