A friend and I were talking about this verse, and were wondering about how God directs our paths. Her translation said that God “will make our paths straight”, but I feel this translation is more helpful for this lesson. (All translations here are HCSB)

Trust in the Lord with all your heart,
and do not rely on your own understanding;
think about Him in all your ways,
and He will guide you on the right paths.
–Proverbs 3:5-6

I was reminded of this from the prophet Isaiah –

Therefore the Lord is waiting to show you mercy,
and is rising up to show you compassion,
for the Lord is a just God.
All who wait patiently for Him are happy.
For you people will live on Zion in Jerusalem and will never cry again. He will show favor to you at the sound of your cry; when He hears, He will answer you. The Lord will give you meager bread and water during oppression, but your Teacher will not hide Himself any longer. Your eyes will see your Teacher, and whenever you turn to the right or to the left, your ears will hear this command behind you: “This is the way. Walk in it.”
—Isaiah 30:18-21

God will direct our paths, telling us which way to go. This will make our paths straight, because God is keeping us from straying to the left or the right. This phrase is used often in the book of Joshua. Here is one example –

“Be strong and courageous, for you will distribute the land I swore to their fathers to give them as an inheritance. Above all, be strong and very courageous to carefully observe the whole instruction My servant Moses commanded you. Do not turn from it to the right or the left, so that you will have success wherever you go. This book of instruction must not depart from your mouth; you are to recite it day and night so that you may carefully observe everything written in it. For then you will prosper and succeed in whatever you do. Haven’t I commanded you: be strong and courageous? Do not be afraid or discouraged, for the Lord your God is with you wherever you go.”
–Joshua 1:6-9

Jesus echoes the most important part to how this works –

But seek first the kingdom of God and His righteousness, and all these things will be provided for you. Therefore don’t worry about tomorrow, because tomorrow will worry about itself. Each day has enough trouble of its own.
–Matthew 6:33-34

We must seek God first. When we follow God, we won’t get lost. This is how out paths, and our lives, will be straight.

Don’t make plans and then ask God to bless them. That is doing it in the wrong order.
Follow God, and God will fill you with God’s desires, and direct your way.
Then you will go in the right direction.