You'll never trust an answer entirely until you
  experience the Holy Spirit for yourself. Once you
  have done that, you'll better recognize who He is
  and isn't with by their words and actions. People
  have will of their own, and they tend to act out
  of their won will at times, doing and saying things
  that the Holy Spirit is in opposition to, and that is
  when they are convicted of sinning, ergo their conscience
  begins to bother them.

  Then you need to confirm that it is fact "from" the Holy Spirit
  thru study of Gods word, prayer and fasting. The later can be
  dangerous if your health isn't up to par.

  It is dependent on that persons circumstances and what is going on
  in their life, what the future holds in store for them and what
  dangers or obstacles are ahead of them. If you're told by Him to
  drive down road a which is a dirt road, and your friend is told to
  drive down road B which is asphault, and both roads lead to the same
  destination, their is normally a good reason why. Of course, you'll
  have to be sure you're being led by the Holy Spirit first before
  you ever begin relying on the advice. Thats where prayer and fasting
  come in.

  The hardest part you'll ever face is learning if it is Him and that
  you can trust Him. These are questions that other people cannot answer
  for you, as only God and you know you best. It's easy for something to
  be your will and not Gods, and confuse the two, thats when bad things
  start to happen to you. God tests people. He puts them thru trials
  that they would rather not face, one reason is to see if they will be
  faithful and trust in Him, another is to see if they will seek Him
  and His advice thru prayer as well as obey His laws. If you haven't
  done these things than it's a safe bet the voice you hear is your
  own. The best way to meet Gods laws is to trust that Christ died
  for our sin and was risen to life on the third day, and the next
  is the most crucial for by it you will meet the  demands of God
  and Christ...Love God with all your heart and mind, and love your
  neighbor as yourself. Now this doesn't mean that if your neighbor
  steals your tv that you just automatically forgive him, he has to
  speak to you and confess it first, and it doesn't mean that you can
  beat him over the head with it. Gods advice to turn the other cheek
  is the best route to take, but the old testament also gives you the
  right to protect your family and yourself from attackers, killers and
  thieves. I say protect against them, not outright slaughter unless
  they've given you no way out. But those scriptures make it clear
  that should they break Gods laws in their dealings with you such
  as robbery of your home, you're pretty much free to kill them if
  that is what is required to save yourself and your family. You just
  need to keep in mind how God will react to what you've done and
  whether you have met His requirements in scripture or not. But it's
  the same process in every dealing with God on a daily basis.