The way that the Holy Spirit guides Paul and Barnabas’ missionary efforts in the beginning portion of Acts 16 should cause us to give much more consideration to the Spirit’s providential guidance in our lives in the opening of doors and the closing of them.  We’ve all experienced this—We plan to visit family or friends or go to some conference and we get sick or we have car problems or our flight is delayed or the interstate is shut down; our plans are thwarted.  How quickly do we get our minds to think that it just might be God who is hindering our plans and wanting us to do something else?  So what do we do when we run across this?—Do we spend our time chaffing at the providence of God while having a pity party or do we redirect our thoughts to line up with God’s plans?
Is this not what Solomon is teaching in Prov. 16:9 The heart of a man plans his way, but the Lord directs his steps.  The biblical principle is NOT: Don’t worry about making plans because the Lord is sovereign.  Rather, it’s don’t presume that our plans are the best and will always be fulfilled unhindered.  The reverse of that is what James is going after in James 4:13 Come now, you who say, “Today or tomorrow we will go into such and such a town and spend a year there and trade and make a profit”— 14 yet you do not know what tomorrow will bring. What is your life? For you are a mist that appears for a little time and then vanishes. 15 Instead you ought to say, “If the Lord wills, we will live and do this or that.” 16 As it is, you boast in your arrogance. All such boasting is evil.
Keep in mind that this also pertains to great things like missions or where to put a church building or hiring church staff.  We can and must make plans, but we must also keep our hearts in submission to the Lord’s providence throughout the entire process.