If you're not good at what you do, why do you do it? If you are good at it, why do you doubt yourself? There's a time and a place for humility, for self-questioning and for submitting yourself to the learning curve of difficult experience. There's also a time for being proud, strong, sure and certain. You're not pretending to be well placed to help someone now... nor are you in your current situation by mistake. Be gentle and tactful by all means, but be strong enough to ensure that the right things happen in the right ways.