If your topic is:
What is the effect of too much lactic acid in the body during exercise?
1. Identify keywords or phrases:
lactic acid exercise
2. Explore synonyms for your keywords/phrases:
exercise: exertion, movement
lactic acid: milk acid, lactonic acid
What is truncation? Truncation is removing the end of a word and replacing it with a symbol. So why would you do that? Because it will search multiple versions of a single word without you having to type them all in.
To truncate a search term, do a keyword search in a database but add an asterisk (*) to the end of the word after you've cut off part of it. Confused? See the example below.
For example:
Instead of putting in exercise, exer* will search for exercise, exertion, exert, etc.
You will get more search results if you truncate!
Once you have collected some articles, take a closer look at them.
Read and review what you have. Do you have enough information to support your topic?
If you do not like what you have or you do not have enough good information, go back to your search. Try some new keywords or a different database.
Explore some of the subject headings from the articles that you do want to use.
If some of your articles have bibliographies you might want to look at some of the sources listed in those bibliographies.
If you are stuck -- ask a librarian for help!