The (Almost) Most Important Decision to Make When You Start a Website:The Domain Name

Choosing a domain name may be the most important step in starting a new website

I said maybe in the title of this post because there is the also the question of the subject the website is about. Most likely, a domain name related  to subject will be preferred.

I think that the domain name may even be more important than the subject

There is a market for used domain names. There appears to be a "sandbox" for new sites with new domain names at Google. This means that any new domain name is put on hold for really great search engine ratings till it has aged for a few months. This is supposed to help keep spam sites (sites just made to get high ratings to get advertising clicks) from going straight to the top. Much of this is theory, since Google does not share its methods with anyone. Still, there is a market for older domain names that have been hosting some kind if content.

Even if you don't plan to sell your domain name, it may be just as important as the subject of your site

I was originally thinking of using subdomains for extra web sites ( I sill might ). A subdomain is a separate part of another domain. It looks like this www.subdomain.maindomain.com. This would save a bit in creating additional websites. It saves from purchasing the additional domain. It also saves on hosting. Many hosts allow you to add subdomains at no extra cost while they often charge for additional full domains.
Using subdomains, you could save a lot of money on testing ideas for niche sites by making each site a subdomain. Even if this does not give a penalty on the search engines (I have not been able to determine a real yes or no on this question), not having a separate domain name for a site could really cause problems later if you need to change hosts.

Three reasons you may need to switch Web hosts

• One or both domains you have sharing a host are beginning to require large amounts of bandwidth or disk space. You simply may not be able to get enough from your host with one account.
• If a site is generating a lot of income, you may need a more robust host. No matter what the claims a discount host provides, you will experience downtime at some amount point. Really tough backup systems will cost more than you will receive at any discount host. I have a site on one host that experienced a 1/2 hour connectivity outage. This has happened once in over two years. This was a major breakdown by their standards and generated an emergency email even though I did not have content up. They also provide constant and regular backup (and restores when you need it). Another host, recently lost power to all their servers for nearly a day. This was a major breakdown by their standards. They never notified me directly and I would not have known had I not been trying to update the site at the time. They also charge if you need them to restore from a backup. You get what you pay for and should not really expect everything from a discount host. If your site make $10 a day if it is down one day you don't lose much. If your site makes $100 a day it would definitely be worth the extra monthly charge to make sure it is up and has better backup and redundancy in place.
• May need more CPU time for a site than you get with a shared server. If your site uses databases heavily, even if your host provides high bandwidth, if you share that server with too many other sites that use the same CPU, your site may seem slow.  Also, even if you have a high monthly allotment of bandwidth, your host may not be able to provide a wide enough pipe during a peak period (the fabled site that crashes from volume during a Super Bowl commercial).

Of course, maybe you chose a bad host to begin with

You can read a bunch of horror stories one blogger has had with web hosts here.
www.jimwestergren.com
Sticking to better known Web hosts will help you avoid problems like he has had. Yet, even well known hosters will experience some outages like I said above. At least with a well known host you can expect that there is actually someone there to fix problems (not off to university).

Just Switching domain names later on can cost you

If you decide that a different domain name for your site would be more effective, you may pay a penalty with the search engines when you change. Even if you provide the proper redirects and try to notify the search engines and keep all your content the same.
You can read how one blog has had some problems after changing domain names here.
www.paulallen.net

A domain name will make you independent of the host you choose

This is one reason you should purchase your domain name from a separate registrar like GoDaddy. Your domain name will be completely independent of your host. If you need to switch to a new host for any reason, it can be very quick and painless. Just sign up with the new host. Then transfer a downloaded backup of all your data over or recreate it at the new host. Finally, just change the namservers at GoDaddy to point to your new host. Your all done. You could be up on the new host in just a couple days or even hours (depending how long it takes for the domain to go propagate and point to the new nameservers. There should not be any penalty with the search engines this way either.

I suggest choosing your domain name carefully

You will not want to change it later. Make sure you use an independent registrar like GoDaddy. Use a separate domain name whenever possible for additional sites.