A good Website is

To me, summarising a good site isn't easy. There is so much a site can offer, and while a good layout IS excellent, it HAS got to be said that it is the content you are there for.
But then, how can you read a site if you can't read the layout? See why this is hard? >.>

Ok, starting point. Content. You need to have some if you're going to make a site. After all, isn't that why you want to make a site? Because you've got the content to fill it? A good idea is to get your content organised first, then build the site. No one wants to see a half finished site with "Construction" signs everywhere.
Your site needs to have a purpose. Graphics. Blog. Hosting. Anime. Whatever it may be, it needs to have something that will make readers want to read it. Whether it be information on their favourite Anime, or Graphics for them to use on their site.

A good thing to remember is if you're going to offer something, such as Graphics, you need to provide a mature and professional layout and language. Otherwise people just won't take you seriously.
I know I said it's the content that mattered before, and believe me it is, but you need to have a good layout. If you're offering something, this shows off your skills. Remember, first appreances are everything. If a visitor came to your, say, Graphics site, saw you had a wonderful, organised layout, they're going to want to see those Graphics!!

You must be careful about the language you use. People don't appreciate swearing, violence, ect. People also hate it Wen U rite like dis. oR wEn YoU wRiTe LiKe ThIs. It's hard to read, and looks really immature. Just..don't!

You need to be wary of your colour scheme. It is best (This is what I do) To pick one colour, say red, and have it as your base colour. Then, stick to shades of red for your site, the text ect. Of course you need to place things so that they are readable. There is no point having a BRIGHT red text colour and a Dark red background. It just won't work.
Make sure you always appear friendly, this will make people want to talk to you, and get to know you. It will also want people to visit your site. A friendly owner makes a friendly site.
You need to give your site lots of attention. Don't make it, update it once, then leave it just for people to view. I'm always looking for ways to make my site better, so I'm constantly working on it. Maybe it's just the perfectionist in me talking, but I feel there's always at least one more thing you can add to your site. Plus, if you show determination, it will really show.