singpeace offers great advice as usual. Couldn't have said it better!
The only thing I'll add is that we have to be careful not to confuse a negative inner voice that whispers condemnation.
That's true, and common -- if you are open to hearing from quiet supernatural sources, other things pop in there too. Learning to discern takes patience and attention. And it's not necessarily something that one locks into place after a few years of successful discernment -- we always have to stay on our toes.
Both the Old and New Testaments are crucial for understanding who God is, how He interacts with people, and what He hopes for us. We have one God, who has not changed. His terms for forgiveness have changed with the new covenant.
The more of His Word you put in your brain and heart, the closer you will come to understanding what His will is, and what His voice sounds like. His Word will be anchored in your soul, and written on your heart.
When it comes to daily decisions, you might not always know. There are issues of sin vs. doing good, but so much neutral area in between. It is not a sin to go for a walk or attend a meeting, but there might be a point during those activities where we realize we are slipping.
Maybe someone asks us to take on leadership in an area we don't fully agree about. Or we slander someone when we're in a group of people who think similarly and get the adrenaline going with negative talk.
We need to be responsible and spiritually proactive in any situation. Stop the downhill conversations before they get into the muck. The more you treat each moment as an opportunity to serve Him, the more you will feel His Spirit well up in you.
Psalm 19
1 The heavens declare the glory of God. The expanse shows His handiwork.
Day after day they pour forth speech, And night after night they display knowledge.
There is no speech nor language, Where their voice is not heard. Their voice has gone out through all the earth, Their words to the end of the world. In them he has set a tent for the sun, Which is as a bridegroom coming out of his chamber, Like a strong man rejoicing to run his course.
His going forth is from the end of the heavens, His circuit to the ends of it; There is nothing hid from the heat of it.
The law of the LORD is perfect, restoring the soul. The testimony of the LORD is sure, making wise the simple. The precepts of the LORD are right, rejoicing the heart. The mitzvah of the LORD is pure, enlightening the eyes. The fear of the LORD is clean, enduring forever. The ordinances of the LORD are true, and righteous altogether.
More to be desired are they than gold, yes, than much fine gold; Sweeter also than honey and the extract of the honeycomb.
http://new.studylight.org/desk/?q=ps 19:11&t=en_hnv&sr=1Moreover by them is your servant warned. In keeping them there is great reward.
12 Who can discern his errors? Forgive me from hidden errors. Keep back your servant also from presumptuous sins. Let them not have dominion over me. Then I will be upright, I will be blameless and innocent of great transgression. Let the words of my mouth and the meditation of my heart be acceptable in your sight, LORD, my rock, and my redeemer.