Databases usually default to AND as the primary operator and connect concepts tied together with AND first. You can use parentheses ( ) to indicate to the database how you want your terms to be connected.
Truncation is useful when you have search terms that are "root" terms. For example: teen, teens, teenager. By adding an asterisk * to the end of the root term you can search for all the variations in one search.
Wildcard searching is useful when you have multiple spellings for a word. For example: color vs. colour. You could use the wildcard ? to ensure your results include both variations of the spelling: col?r