You can learn a lot about the Friar's understanding attitude by his first speech. He says things like, "And, from her womb, we find children of diverse kinds
When we are sucking on her natural bosom;
Many plants are excellent for many virtues,
Some have none, others have some, but are all different."
He realizes that different people have different virtues and thusly you can tell that he won't be opposed to helping Romeo and Juliet. However, he is not naive. Friar Laurence tells how plants contain both poisonous and healing powers. If a plant’s use is abused, the result is harmful. “Virtue itself turns vice, being misapplied, / And vice sometime by action dignified.” He applies this same lesson to man, who possesses both good and evil within him. If man allows the evil to become predominant in his life, it will destroy him.
You can tell that the Friar is good with plants and can make potions and such. He also foreshadows how some potions meant for good can turn out to be hurtful, even fatal. You know the Friar is also very clever, and this will come into use later in the play.