First, I think one has to ask themselves if the message lines up with the Word of God to determine if it is truly from God.
Beloved, do not believe every spirit, but test the spirits to see whether they are from God.
1 John 4 NKJV
My experience wasn't anything earth shattering but I believe it was the Holy Spirit that was pushing me. One day a few years ago, I was going to our local Walmart and as I drove into the parking lot I noticed a fellow sitting along the curb. He had a sign asking for money to buy food. Around here this is an extremely rare sight. We just don't encounter people begging in our small town of about 10,000. My first inclination was to just ignore him and I proceeded to park my vehicle and pick up whatever it was that I needed. On my way out I drove by the fellow again and just ignored him but as I did I suddenly felt this urge to do something no matter how small and the farther away I drove the stronger this urge became until finally I felt I needed to turn around and go back to that parking lot. I had a small pocket sized New Testament from the Gideons in my truck glove box and a $20.00 bill in my wallet so I slipped the money inside and handed it to the guy. He thanked me saying "God bless you!" I told him that the thanks go to God and left. I did not know him and never saw him again so I do not know what seed I may or may not have planted but I sure felt a load lift off my shoulders when it was done.