You're all excited as you're about to set up your very first web presence. Do you really know what you're letting yourself in for?
Before you go anywhere else, you first stop will need to be a Domain Registrar. This is where you'll rent your domain name - the address of your website.
Notice I said 'rent' rather than buy. This is because it's yours subject to you paying an annual fee. Be aware of this before you start. It's not yours for life!
If you've already decided on a niche - the topic you're interested in, then your first thought would probably be to get the niche-name, if possible, which chances are it may not be available. Unless...
... You are willing to settle for a more obscure TLD or Top Level Domain. That's the bit at the end. You know, like .com .org or .co.uk - These TLDs used to have a meaning .com - commercial .org - a club or organisation .co.uk - a UK based company, but these days it's a bit more of a free-for-all. There are some TLDs where you have to reside in the country or at least host your site there, be a government based body to use .gov or be a registered educational establishment to get a .edu
There are new TLDs being set up all the time and if you're set on a particular word for your domain name, then you mustn't mind an obscure TLD.
On the other hand, if you've decided you definitely want a .com then you will probably have to compromise on your domain name.
Some good ideas - a single hyphen between words. I wanted stevenlucas.com but someone had beaten me to it, so I got steven-lucas.com instead.
Depending on your idea for the site adding a slight extension to your niche could work - fishing.com is already taken, but fishing-uk.com might be an option (I don't know. I haven't checked).
At a push, you might want to try 2 hyphens but think about explaining 'play-guitar-with-steven-the-rock-god.com' to someone. You have to tell them about all the hyphens and it gets to sound silly when you say it out loud.
Some bad ideas - Brand names - unless you own the brand, somebody legal will start chasing you with cease and desist orders and a judge could just take the name off you and give it to the copyright owner.
- Expletives and swear words. Not always intentional, but something to be aware of. The town website of Scunthorpe in the UK was delisted by Google, not for its content but for the 2nd to 5th letters of the town's name, at east until somebody pointed it out to Google.
So there it is. More than you really need to know about domain names. Have fun choosing yours.