Do Your Keyword Research!
Select a niche and then go even further and narrow it down to a specific niche you want to have your website about. Example: Let's say your niche is about cats, you then need to narrow it down to a specific area dealing with cats. Like, type of cat, proper care of your cat, proper food for your cat, toys for your cat, etc. As you can see the list can be endless. You can actually take one of the above choices and narrow it down even further. The more specific you are with you niche, the odds are more in your favor of being successful.
After you have chosen you niche, go a search engine and enter google adword keyword tool. This will bring you to google's keyword tool where you can then begin to check out the keywords you have selected. Select at least ten keywords for your niche and then do a search for each specific keyword and see what the results are. Also check and see what the competition is for each keyword you select. If the competition is high then you are going to have a tough time achieving a first page ranking.
If you are just starting out, I would try to select keywords for you niche that has a low to medium competition range. You can do either a broad, exact or phrase search of your keywords. This can take some time, but that is okay, as you are trying to find keywords that will give you the best results for your chosen niche. Once again, I can't tell you how important this process is. Your have to have good keywords that relate to what ever your niche is. Many people throw together a website with either poor keywords, or worse yet no keywords and then can't understand why their website isn't found or has poor listings in the search engines.
Once you have selected your keywords, it is now time to select your domain name for your site and see if it is available. Go to one of the the websites that does domain hosting, like hostgator or godaddy and see if the name you want for your website is available. If possible try to get a domain that contains one of your top keywords or keyword phrases. Here is an example of a keyword phrase, "bestbiblemovies", I was able to use to secure the domain name, bestbiblemovies and am currently listed as number 1 ranking on page 1 for that phrase.
If possible, purchase a .com domain name and not one of the other listings that are offered. A .com listing will give you better results with the search engines. I hope that this have given you a little insight on keywords and how you can be successful when you go through your keyword selection process.