How do you discern if you are hearing from the Holy Spirit or from Satan (or just your own sinful nature)? Consider using these two questions and a pondering:
Is the thought in line with Scripture or not?
Is the thought glorifying to ourselves or to Jesus?
Remember that the Holy Spirit will only counsel us in the will of God, which is our sanctification.
Therefore (as most clearly seen in the case of knowing the will of God), when we are faithful in pursuing Christ we will be continually reshaped to His likeness and our desires will match His own, allowing us to be instinctively drawn towards that which He wants for us, and we can then know how to speak, which job to accept, where to live, who to marry, which charity to give to… simply because our preferences will match those of Christ.
Essentially it all boils down to our relationship with Jesus; if we ache to know Him more and He is our absolute priority then we will know His voice and can discern His direction. (“My sheep know my voice and they follow me.”)