When it comes to spamming Google, some do it on purpose, others it is just by accident. They claim they didn’t know any better, and they’re telling the truth. The problem is, they get whacked in the SERPs just the same.
Here are some things to look out for:
1) Your Domain Name
What does your domain name say about you? When it comes to Spam, plenty. While myself and Bruce Clay have tested that you can have a domain with 10+ hyphens get indexed by Google what does it really look like to the user? Better yet, even if it does get indexed how often it is manually reviewed as a potential Spam site?
Advice: Avoid more than two hyphens in your domain name and concentrate on .com TLD instead of .us, .cc, .info, etc. Those are often looked at as “cheap substitutes” to the real thing.
Myth: Only registering a domain for one year is a sign of Spam.
Truth: No it isn’t – and just because you register a domain for ten years doesn’t mean it isn’t a Spam site either. This is a “mindcrime”. Think about it. With discount registration services, you can often get a domain for ten years for about $70.00 or less. Nothing says “I am committed to this business” as $7.00 a year does. That is garbage and untrue. The length of your registration means nothing.
Tips on Domain Name Registration
2. Copied Content
Yeah, I know we all fall into the bad habit every now and then which we started in high school: innocent plagiarism. But it is plagiarism just the same and it is against the law no matter what country you live in.
Google is cracking down on sites that just offer scrapped (plagiarized content) content with ads.
Advice: If you remove the ads and the copied content do you have anything of value left? If the answer is no, you are treading in “Spamming Waters”.
3) Linking Policy
How is your linking policy? Do you accept all requests for links? Do you have a page which lists links to foreign SEO companies, viagra sites, casinos, payday loans and mortgage refinancing?
Advice: Don’t do that.
Play nice or get whacked by Matt Cutts. 
The main reason I started the SEO Revolution was out of frustration. Frustration at all of the lies and misconceptions that are posted in forums, given as advice in teleconferences, and even taught in live workshops. "So why didn't all of this work?" " Why wasn't my site successful?" " Why am I still stuck in a rut?" 
Jerry,
Solid advice. One question for you. My understanding is that while it easier for a user to remember your domain name without any hypens and may be better for returning clients, it is better seo wise to use hyphens (within the bounds you have set in your post). Which way do you prefer and why?
Hyphens in domains may have worked in the past, but today with the increased power of incoming anchor text, it is less impactful.
I don’t use hyphens in domains names.