Use the different pages/tabs on this guide to find recommended resources (databases, Web sites) and terms (for identifying books on selected topics) when doing your research. Speeches need the same kinds of research as papers--and remember you will have an audience that will appreciate a well-researched, well-thought-out, and well-planned speech.
Depending upon your specific assignment, different library and other resources will be helpful. If you have no or limited familiarity with your topic, using encyclopedias is highly recommended in order for you to learn enough about your topic to get started on more advanced or specific research. An advantage of using encyclopedias is they can give you ideas for what to search for in other resources--names, places, events, issues/concerns, etc. that you might not be able to think of quickly yourself. Terms in hand, the time you spend in catalogs and databases (and even the Web) can be much more effective.
A place that you can find extensive information about current topics is CQ Researcher (CSU affiliates only). Articles include chronology, pros and cons, and bibliographies.
If you happen to be giving a speech in your personal life (it can happen), see the Personal Speaking Web page for suggestions. The second paragraph on the page provides suggestions that apply to any speech.
Just in case anyone is interested, the centenary of the World War I is happening! See World War I for links to primary sources and ways to identify other resources of interest.