Some people say that only a small portion of your research should appear in your speech and the majority will come into play later. I have yet to see the "later". This may be in the form of points of information but that is assuming that you can predict what information you will need to contradict what the speaker says. If you have good information don't keep it to yourself, USE IT.
Look for facts and examples more so than statistics. While statistics can very handy for filling up a few minutes, they are also boring. Your information should back up your argument and be memorable. If you find a little known fact that will surprise the audience and catch their attention use it strategically. Place it at a crucial stage of your speech in a way that everything falls in together and the audience becomes convinced of the truth of what you are saying. Remember that your argument is the most important part of your speech and your research should back it up, not the other way round.
There are invaluable sources of information all around and you will very rarely come across a motion which you can find absolutely no information if you look hard enough.
Type any subject into the Internet and you are likely to get back 100 sites with useful information and "Greater than 250,000" of utter rubbish. However there are a couple of good places to start. On the main page of this site you will find links to a couple of research webpages which give pros and cons about many topics. They are Debatabase.com and Youdebate.com
One important thing to also remember is that if you are a student then it is probable that you will have access to many journals (economist, Time, etc) electronically through the website of your library. I certainly have access to these through my DIT account. There is no need to go out and buy these journals where half the pages will be ads. You can search through past editions to find articles you are interested in. You can also easily print good articles to help fill out your case book. Its free and all you need is a computer with internet access. If you don't have this then ask your library staff about it.
Although you may complain about your campus library (I think that's fairly universal among all students) it is still an invaluable source of information. Look around the sections which relate to your motion and flick through a few books that look relevant. If you don't know where to go for information take the keywords from the motion and type them into a nearby terminal. It should give you the book references you need.
Journals Rooms: This is easily the best source of information on any campus library. If you have a motion dealing with a topical political, cultural, or scientific subject then the first thing you should do is look through the back issues of Time and Newsweek. These contain a huge amount of information and not only on current affairs. If you've never read them it is well worth spending a short time flicking through them so that you get a feel for the sort of information they carry and where to find it if you need it later. If you want more information then there is bound to be some information about it in other more specialised journals but it may be harder to find. You could also look up the past issues of newspapers on microfilm but you really would want to know exactly what you are looking for. Journals rooms may be increasingly replaced by on line tools as mentioned earlier but some articles aren't made available on line until the next edition is printed so sometimes you will have to do it the old fashioned way.
The problem with books is that by the time they are published they are more than likely out of date. However there are books available which give Pros and Cons of various topics. They should be used with caution and not a complete replacement for your own arguments and research but they are a good start point and particularly useful in the first 2-3 min of your 15 min prep at Worlds style events. Not surprisingly the best of these books is called Pros and Cons
T.V. & Radio:
While it is unlikely that TV will oblige you by broadcasting a program dealing with the subject behind your motion while you are preparing for it you can still use them for information. If you know that there is a documentary, special report or debate on a topical issue why not watch, or listen to, it. You don't have to go out of your way or sit there taking notes like a lecture but if you have nothing better to do you might be surprised how much of it you will remember if it comes up later.
This involves a group of people getting together to discuss a motion and come up with ideas. The group meets in a room and trash out the various issues involved from a definition and line to examples and the other sides possible strategy. One member writes down all the ideas and this is best done on a blackboard so a tutorial room is sometimes used. However these can also become side-tracked (one I was at lasted over three hours and only twenty minutes were spent discussing the motion). If used effectively they should work well and we may start doing them on a more regular and organised basis. Even if you don't want to hold a brainstorming session don't be afraid to ask other debaters for ideas, most will be glad to help and may even have debated the motion before. NOTE this is now banned at Worlds so you must have your brainstorming of possible topics done before Worlds.