Sometimes we may have to go against the grain and take chances, just like Abraham went out not knowing where he was going, he took a leap of faith. The Christian life is a journey, not a destination, and no one can say they have "arrived." If we do make mistakes, God turns them into blessings according to Rom. 8:28, which says all things will work together for our good.
David was a "man after God's own heart" and the reason he was is that he was willing to do all the will of God. There is no "1-2-3" method of finding God's will because we are all unique individuals in God's eyes. However, He does have a master plan according to Jer. 29:11 which says, "I know the plans I have for you...." Yes, "let the chips fall where they may," because God cannot be thwarted and He has a custom-made plan for each of His children.
There are many "no-brainers" in the Bible that declare God's will like 1 Thess. 5:18 says, "In everything give thanks, for this is the will of God in Christ Jesus concerning you." We are commanded to know God's will and not be ignorant of it: "Do not be foolish but understand what the will of the Lord is." We have the privilege of being given the will of God: "...[God] has chosen you to know His will" (Acts 22:14). We are not to sing with Doris Day: "Que Sera, Sera, Whatever will be, will be." We are not subject to impersonal fate. Nor can we be like the blind kismet of the Muslims who proudly say in a catastrophe: "It is the will of Allah."
As a matter of definition, there is the preceptive will of God laid out in Scripture, and His secret, sovereign, decreed will that is secret and none of our business. "The secret things belong to the Lord our God, and those that He has revealed belong to us and to our children..." (Deut. 29:29). When we discover the will of God, like an epiphany or "Aha!" moment in the Scriptures, we will have peace (cf. Col. 3:15). We are to claim promises like Psalm 32:8 saying: "I will instruct you and teach you in the way you shall go, I will counsel you with my eye upon you." We can get in sync with God's will by knowing the Word: "I desire to do your will O my God, your law is within my heart" (Ps. 40:8). "Send forth your light and your truth, let them lead me" (Ps. 43:3). "Thy word is a lamp to my feet and a light to my path" (Ps. 119:105). "The steps of a good man are ordered by the Lord, and He delights in his way" (Ps. 37:23). Soli Deo Gloria!