1. For exact matches, put quotes around phrases:
"Gulf oil spill" will only return search results which contain that exact phrase "Gulf oil spill". If you search for Gulf oil spill, the results will return any post contain the individual words Gulf, or oil, or spill.

2. Make sure you make the search "general" enough:
For instance if you are interested in IDP's then use as search argument: IDP OR "Internally Displaced" OR "Internal Displaced" rather than just IDP.

3. Narrow down your search:
...by using the "AND" operator.
If you look for posts related to hunger in Ethiopia due to climate change, then your search argument would be hunger AND Ethiopia AND "climate change".
Beware: logical operators like "OR" or "AND" have to be in capital letters!

4. Force the inclusion or exclusion of search terms:
...by using the "+" and "-" signs.
Haiti +shelter will first take all posts containing the word "Haiti", and then narrow the search to those also containing the word "shelter".
Haiti +shelter -hurricane will return all posts containing "Haiti" and "shelter", but do not contain the word "hurricane"

5. Sorting the search results
By default, the search function returns results based on "relevancy", using an internal algorithm. E.g. an article with your search argument in its title will be quoted as more relevant than if your search argument is only found in the body text.
Once you see the search results, change the way items are listed by clicking on the header line: You can sort search results alphabetically by title, or by source. You can also sort by date, showing the most recent article first or the oldest article first.

6. RSS feeds based on search arguments
You can also build your own RSS feed, based on your search arguments. This enables you to automatically retrieve all the latest articles for the topics of interest to you.