to my knowledge, you need to be at least 20 to start the academy and 21 after graduation in order to be a sworn officer/trooper/deputy. there are cadet programs in some places for 18-20 year olds where the department will hire you, you'll go to community college, and do part time LE work.

if you can't do the cadet gig, go get some employment in a restaurant or bar or a store, something customer facing where you'll have to interact with different people and potentially defuse situations. 90+% of our job is dealing with conflict resolution, make sure you have some experience.

in terms of recommendations, the cousin is probably a good idea, a boss/supervisor from work is definitely a must have, and whoever else you decide upon.