What's in a Name?
Finding the names of your Dutch ancestors can be confusing, until you realize that most Dutch people didn't use surnames until 1811, when emperor Napoleon forced the Dutch to register and adopt a distinct surname. (The Dutch United Provinces was invaded by France in 1795 and annexed in 1810.) Most Dutch people of the time didn't think of this as an important thing which would forever change their family's name--most thought it was a current fashion based on politics. Therefore, many adopted names based upon their job or object--like Bakker (baker) Boekebinder (book binder/publisher), Boter (butter). Others decided to go the imperial route, and chose names like Keizer (emperor) or de Groot (the great). Sometimes the names were geographic--someone named Van Dijk may well have lived near a dike. Other names, which one would think were surnames chosen in this fashion--such as Kuiken, which means "chicken"--are actually some of the oldest surnames in the Netherlands. (Kuiken and its other forms such as Cuijken, van Cuijk, and Kuijken--have been around as a formal surname in the Netherlands for many hundreds of years.)
Prior to 1811, if a family had a surname from one generation to the next this could hint at a family of reknown, wealth or historical significance--such as the Wassenaars; a line so ancient that it is near-impossible to learn which came first--the surname or the town.
For most Dutch people however, a patronymic name was used. This patronym would be the first name of the person's father; so a man named Dirk who had a father named Jan, would be named Dirk Jans. When Dirk married and had a son named Jacob, that son's full name would be Jacob Dirks.
Earlier patronyms were sex-specific: Let's say that Jan had two children--a son named Dirk and a daughter named Antje; Dirk's full name could be written as Dirk Janszoon ("zoon" means son) or abbreviated as Dirk Jansz. (with the period at the end) Antje's full name could be written as Antje Jansdochter or abbreviated as Antje Jansdr.
People who used surnames sometimes used patronyms as their middle names, as well--so, if Jan had a surname (Otte) then his son Dirk could have been named Dirk Jansz. Otte.
Online research tools
If you're of Dutch ancestry, you're in luck--it is very easy to research your family tree and obtain birth, death and marriage records for many hundreds of years. [Cyndi's list] is the largest list of links to Dutch genealogy tools on the internet. [Genlias] allows you to research records in Dutch or English, by surname, patronym, or both.
Language and shifting borders
Once you begin to amass records, how do you understand them? Online tools such as [Babelfish] allow you to translate records from Dutch to English; however, if your ancestors are from Friesland, your records may well be in Frisian--and there are no online translators for this but there are online [dictionaries] to help you muddle along. Sometimes, your "Dutch" document might be in a language other than Dutch--this author has a Dutch birth certificate written in German, for example. This could have happened as a result of shifting borders over the years; your Dutch ancestor may turn out to be German, Flemmish, or Belgian, depending upon the region and what the country's borders were then!.
If let's say your particular ancestor is the above-named Dirk Jans. You find his Dad, but the record you find says that Jan's son Dirk died at the age of three--so this can't possibly be your ancestor. That doesn't necessarily mean that Jan had no other children named Dirk! A common practice was to name the next child after a child who had died; so it is possible to find a Dirk Jans born in this ficticious family two or more times. So keep looking!