The other “H” word is really the first step in avoiding sin: Humility. It leads to all the other virtues.

This. But make sure it’s true humility. Humility, by the way, and being honest with yourself go hand in hand (by the way, if you’re honest with yourself, it’s quite difficult to be dishonest with others). True humility is understanding your faults and allowing the Trinitarian God to take you, faults and all, and make you strong in Him. A humble person knows what their faults are, is honest with him/herself when he/she sins, and yet understands that God loves him/her anyway and wants to genuinely allow God to work His will through him/her.
Because, remember, as sinful and as destructive as hubric pride can be, scrupulosity is just as bad, as it is paralyzing. A prideful person doesn’t think he/she needs God. A scrupulous person doesn’t believe that it is possible for God to love him/her. In other words, a prideful person doesn’t think he/she needs God’s mercy. A scrupulous person thinks that God’s mercy isn’t strong enough to save him/her.
Regardless, though - the key to humility is to make
good examinations of conscience followed by
good confessions. For the most part, this is what most of us need. If, however, you start falling into scrupulosity (and by this, I mean, you think just about everything you do is a mortal sin), a good confessor is needed to help you discern which of your actions are actually sinful and which ones are not.