For me, encountering the Holy Spirit feels like pure peace, when fully immersed in the presents of God, Satan cannot attack or harm me; for I am with Jesus. The Holy Spirit brings an awesome happiness, a happiness which is true and doesn't compare to Earthly joy. In this time with Jesus, insight is always gained and my faith is increased. Also I usually cry tears of joy or feel the need to speak in tongues. The most likely times of having these encounters are when I am either worshipping the Lord or have been prayed for. This is my story anyway.
I am not for a minute saying this is how everyone is going to encounter God's spirit, because God is original. This is just me. God has something wonderful planned for you. Just wait on the lord and you will see. The faith life is an adventure and your path will be different to others.
But you will know whether or not you are encountering the Holy Spirit, because you will feel at peace as a result of its manifestation, and you will be surprised as God opens doors for you at this point in time.
Overall, keep close to Jesus and you will feel His awesome presence and pure peace. I hope this piece encourages you.