Searching for a PhD position starts with letting your network know you are available. Although PNN has the opinion that PhD positions are filled according to the Code of Conduct for the Recruitment of Researchers of the European Commission, and that recruitment is done according to these open, objective and public procedures, this is not always the case. Many PhD positions are filled through the professor's network. Therefore, it is good to inform your academic network that you would like to do a PhD.
In addition to networking, you can search for a PhD position outside your network. This can be done through newspapers, magazines (such as Nobiles) and the internet. Moreover, there are several websites that offer vacancies for positions in academia, we list them here:
Academia (the Netherlands)
http://www.academictransfer.nl
http://www.euraxess.nl
http://www.pcdi.nl
Academica (Europe)
http://www.euraxess.eu
http://www.daad.de/deutschland/index.en.html
http://www.qreer.com
Academica (Globally)
http://www.careeredu.eu
http://www.nature.com/naturejobs/index.html
http://sciencecareers.sciencemag.org
http://www.phdjobs.com
The websites of universities and medical centres also have open vacancies for PhD and postdoc positions, and there are many research and graduate schools that post vacancies for scientific personnel on their own websites.
If you want to look for PhD positions outside the Netherlands, you can also look at http://www.gradschools.com. On this site you can find links to graduate and PhD programmes around the world.
On the website Academic Transfer you find an overview of the most recent open PhD and postdoc positions.