Finding accommodation in Brussels may be difficult, but not impossible. Just don’t expect the Commission to provide you with accommodation, because it won’t. Not because the Commission is selfish, but because there are simply too many people coming in at once and no available buildings to accommodate them. The Commission is not a university and it doesn’t have a campus either.
Depending on each case, and I mean your case, you might want to consider one of the following (and not necessarily in this order) options: be on your own, rely on a friend who already lives in Brussels or is coming to Brussels to do the stage with you, or use a hostel.
If you’re on your own, then you should start with practical information link from the placement offer e-mail you received. The link is at the bottom of the e-mail, click on it, then browse along and you will find loads of valuable pieces of information to read, including an example of lease contract in both English and French. It will lead you to the website from the Stage Committee (a body of a few trainees representing all the EC trainees based in Brussels). Although I’m not a great fan of their website (too chaotic for my tastes), they do have a section where they post accommodation (or housing) ads. It can be anything from a room (or kot) to a studio or an apartment. In addition, their website has links to online real estate agencies in Brussels. Look on the ads, make some calls, write some e-mails to landlords and try to settle things before arriving to Brussels. At least, this is what I did and it took me over a month. At the time, I didn’t really have friends in Brussels.
Also, if your budget allows it, you can even make a trip to Brussels to visit apartments. Another option would be to walk around neighbourhoods and look at the yellow/orange A LOUER/TE HUUR (to rent/to let) ads in the windows of available properties.
Having friends in Brussels is the ideal solution, in my opinion. They could lend you a hand to find a place to live and, if they are generous enough, they can offer to host you till you find something. Even if you stay temporarily at a friend’s place, you could still try to find accommodation through one of the ways mentioned above.
A third option would be staying in a hostel. Although I’m no fan of hostels (been to one once and wouldn’t repeat the experience), I know that there are people who love the idea, so check again the practical info link where you’ll find the websites to quite a few hostels in Brussels.
I’m not sure if you are aware, but the Traineeship Office provides two computers with access to internet, as well as two telephones, in their headquarters at Madou Tower. You could make use of them if you come to Brussels and have no internet connection and no phone (though you might consider buying a SIM card). It’s all for free and all meant to help the future trainees find accommodation.
If you are more of the traditional type, you could find ads in the local press: Le Soir, Le Vlan or The Bulletin (issued in English).
I would like to remind you that paying rent or guarantee in cash or by Western Union, MoneyGram, etc. is NEVER recommended. There are plenty of stories of trainees who naively lost their money. Don’t help increasing their number!
And if you don’t have enough money with you when you arrive in Brussels, have no shame to ask for a loan to the Stage Committee (aka Liaison Committee).