When selecting a search strategy, there are a few things you should ask yourself:

Am I looking for specific data? 
If so, use a keywords-based search. 

Do I want to "surf" the Net, looking for interesting sites?
If so, use a menu-based search.

Do I know which keywords to enter? 
If you aren't sure, consider using a menu-based search.

Is my search urgent? A menu-based search is more convenient, but it may make your search longer.