Singing praises to God or worshiping him opens up a window to heaven. As your praise reaches the heart of God, it becomes a two way stream of communication. As you touch God with your praise, his Holy Spirit touches you and ministers to you. Praise and worship can also open the door to blessings from God.
We praise God because he is worthy of all praise. He is the maker of Heaven and earth and the entire universe. He has given us life and through his son has saved us from eternal damnation. He loves us completely despite of our short comings and sinful nature.
Probably the best examples of how to worship the Lord can be seen in the life and Psalms of King David.
God described David as a man after his own heart. David loved God and God loved David. David had a wonderful musical talent and regularly came before the Lord in songs of love and thanksgiving. He danced and played music to praise God. In (2 Sam 6:14-15) it says

And David danced before the LORD with all his might; and David was girded with a linen ephod. So David and all the house of Israel brought up the ark of the LORD with shouting, and with the sound of the trumpet. (KJV)

David wrote beautiful words to express his deep devotion and love for God. David actively pursued God, and desired to have a close personal relationship with him. This is demonstrated in (Psa 57:7 10) where he writes

My heart is fixed, O God, my heart is fixed: I will sing and give praise. Awake up, my glory; awake, psaltery and harp: I myself will awake early. I will praise thee, O Lord, among the people: I will sing unto thee among the nations. For thy mercy is great unto the heavens, and thy truth unto the clouds. (KJV)
When we praise God we are allowing the Holy Spirit to speak through us directly to our Father in Heaven. The Holy Spirits presence can be felt right inside of us and surrounding us as we speak to the Father through him. I have heard many times of healings taking place when people have been worshiping God, and I believe this is because the power of the Holy Spirit comes upon them and ministers to their needs while they are praising God.
There are several different Hebrew words used in the Bible to denote praise and worship. These can be translated into the following English meanings.
Worship - To fall down prostrate (especially reflexively in homage to royalty or God), to bow down, crouch, fall down flat, humbly beseech, make or do obeisance, do reverence or to stoop.
Praise - Literally to use (that is, hold out) the hand; to revere or worship (with extended hands); intensively to bemoan (by wringing the hands): give thanks, rejoice; a celebration of thanksgiving for harvest, to kneel; by implication to bless God (as an act of adoration) or congratulate.

The main difference between worship and praise is that we worship God for who he is, and praise him for what he has done.
You will see that many of these translations display the theme of humility of coming before God in subservience and in reverence of his awesome power. We are not praising him as we would a child who has done well, from the viewpoint of someone who is older and wiser we are to praise him out of our total unworthiness to even be in his presence. In humility we need to grasp the magnitude of his awesome power, love and grace and praise him for them. We need to praise him for loving us despite of how unworthy we are of his love. We need to lift his name on high, not because of who we are, but because of who he is.