Please first read How to Prophesy Over Your Life, so that you can learn the steps of speaking life over your life.
After learning How to Prophesy Over Your Life I suggest that you combine praising God with prophesying so that you can achieve astounding results.
We can a good example of this after God drowned Pharaoh and his army in the Red Sea (Exodus 14:27-28) because the Israelites begun to sing to God and praise Him by saying:
I will sing to the Lord because He has triumphed gloriously!
The horse and its rider He has drowned in the sea!
The Lord is my strength and song and He has become my salvation.
He is my God and I will praise Him. (Exodus 15:1-2)
They then continued and begun prophesying by saying,
People will hear and be afraid.
Sorrow will grab the people of Philistia.
The rulers of Edom will be dismayed.
The mighty men of Moab will tremble.
The people of Canaan will melt as fear falls on them. (Exodus 15:14-16)
And this is what happened because many years later, when the Israelite spies went to Rahab's house, she said to them, I know that the Lord has given you this land and that terror of you has fallen on us and we are all fainthearted because of you because we have hear how God dried up the Red Sea for you when you came out of Egypt. (Joshua 2:8)
Therefore when you get one victory, sing praises to God to thank Him and then start prophesying about the next victory you are expecting Him to help you win.