Don't bother too much with Google Trends, you won't get an accurate picture of the search volume. Sign up for Adwords and use the keyword planner tool.
If you see a trending topic in Trends and do want to write about it, use the Adwords keyword planner tool to find the most appropriate keywords to target. However, keep in mind that trending topics are usually highly saturated and it will be extremely difficult to rank for a keyword relating to something that is trending in Google.
Keywords help Google notice your article but you'll need to build up authority through backlinks and other means before Google will even consider ranking your article higher than one of the top position articles. When you find a keyword you want to use, search for it in Google, then check the top results to get an idea of the competition you're dealing with. If you can't beat those sites, you'd be best using a different keyword.