How did John Adams contribute to the founding of America before the Revolution? Having trouble finding evidence for strictly BEFORE the Revolution.

This depends on where you start the American Revolution; one common start date is April 19, 1775, with the Battles of Lexington and Concord.  Adams was already quite influential by then.  He was a civic leader from his hometown of Braintree, Massachusetts, and a prominent lawyer.  His most important contribution before the Revolution was his legal defense of the British soldiers who participated in the Boston Massacre in 1770.  During the Boston Massacre, British soldiers fired into a large group of colonists who were protesting British taxation in front of the local customs house.  The British soldiers were outnumbered and the situation was tense. During the confusion, the soldiers fired on the civilians, killing five and wounding three.  If it was up to the people of Boston, the soldiers would have been quickly punished.  Adams insisted on giving them a fair trial, with the harshest punishment being flogging.  While some accused Adams of being lenient toward the British, he insisted on giving these soldiers a fair trial.  
https://www.history.com/this-day-in-history/the-american-revolution-begins

https://www.revolutionary-war.net/boston-massacre.html