This is particularly a stumbling block to us, the younger we are. Personal conceit is the greatest mistake for a believer, a seeker after the Lord.
What can I do about it? Look at the second part of this verse: here are the great antidotes to over-trusting our own judgement. ‘Fear the Lord, and depart from evil.’ It does not at first sight look as though it is connected, but it is. You get a good view of God as you sincerely worship him and remember his eternal nature, his infinite power and glory; there is nothing like that to humble the sinner, to humble the individual Christian. Remember grace, fear the Lord, remember his wonderful mercy to you. It is only by mercy that you stand. Fear to grieve him, worship him, that is very humbling.
And secondly, focus on avoiding sin. Why, if I examine my heart every day, and if I really do repent of my sin every day, and if I focus on battling against my faults and my weaknesses, that will take away my conceit and my pride. Solomon helps us here - Be not wise in thine own eyes; fear the Lord, and shun, depart from, evil. Get on with fighting the battle against all your faults and your failings, that will keep you humble says Solomon. So we are helped.