It is anything BUT easy. A few basics, and without these, forget it:
Get married to a Dutch citizen. Bypass that, and you have two strikes against you already. I don't even know if that is feasible under the current circumstances, but get it done. Have the docs certified by BOTH countries.
Learn Dutch. Learn it well. I mean, learn it to the point where you don't need an interpreter. It is a fact that almost everyone in the Netherlands speaks decent English. Big deal, so they're an educated society. If you want to live and work there, you have as much chance of making it speaking only English as you would have trying to get residence and a job in your town if all you can speak is Dutch. And start taking intensive courses in it BEFORE you leave the States. A Dutch immigration official will take you far more seriously if they think you really mean it about becoming a part of their society.
One bright spot about their language--when spoken, it may seem at first like unintelligible gibberish if you aren't familiar with the language and its quirky vowels and consonants. Dutch is nonetheless a Germanic language, just like English, and many similarities will become apparent the more you get into it. If your native language is English, you have a hidden head start with Dutch. Don't give up after the first few lessons, and say it's hopeless. It's not. The Netherlands is quite aware that most immigrants (outside of South Africans, Surinamese and Indonesians) will have a hard time with the language. Prove to them that it is an obstacle you fully intend to overcome, and you have already reached first base with them. They have free schools all over the country to help. Most non-residents who acquire near-fluency in Dutch do so for work-related reasons (like me). It is never expected of non-residents. Americans, in particular, are famous at being total disasters with other languages. Prove them wrong, and you will have already made some friends.
Have a credible job plan. Be ready to tell the Dutch what your skills are, how you plan to use them, and in what field. Aquatic engineering, molecular biology, auto mechanics, SOMETHING. If a steady job is not already offered, a few interviews planned, with written back-up to prove it, would help. Have any professional experience or some recommendations? The more, the better.
They will also ask about financial security. If they even get a whiff of a hint (no matter how inaccurate) that he plans to acquire residence, then go on welfare and watch DVDs all day from his girlfriend's couch, not only will he not get residence, they will stamp his passport with a notice that he is not to be let back into the EU after putting him on the first plane home. This is why the job plan is so vital if he can't present a hefty bank balance.
Health insurance! They will want to see that his health insurance is current and valid for a time long enough that he will be installed in his Dutch employment before it runs out.
If that sounds like a huge wall of obstacles to discourage people from trying to move there, the impression is quite accurate. The Netherlands is a small, very crowded country, and the EU in general is most definitely NOT in need of more people. However, if you have a legitimate reason for moving there (and marrying one of its citizens definitely counts), and are deadly serious about becoming part of the society of the country you are moving to, they will not only let you in, but help you adjust.
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