1. Define your research question.

What are the causes of addiction to smoking among teenagers?

2. Identify the main keywords. 

1. teenagers
2. addiction
3. smoking

3. Pick synonyms for each keyword.

Keyword 1                     Keyword 2                           Keyword 3

adolescents                     substance abuse                  tobacco 

young adults                    dependency                         cigarettes

teenagers                        addiction                               smoking

(teen* or adolescen* or "young adult*") AND (smok* or cigarette* or tobacco or vap* or E-cigarrette*)

 pregnan* AND "drug abuse"

"doping in sports" AND steroids

marijuana AND (law or legislation or "drug legalization" or "narcotic law*")

addiction AND biolog* AND (cause* or etiolog*)

addict* AND (treatment* or therap*)

(substance abuse" and addict*) AND treatment* AND (recover* or recidiv*)

Opioid* AND community AND respon* AND treatment*