The contiental Army had a strong military leadership including George Washington and the Marquis de Lafayette. These leaders made good decisions throughout the war to help the army and defeat the British.
Where are the colonist's at?
During the revolutionary war America had a alliance with France. This greatly helped the American cause because they were able to revieve funding men and other things from France in order to beat the british.
The british were fighting in the Contiental Army's backyard. The soilders knew their way around the land unlike the british. They were fighting on their home turf.
Where is the money!
The Continental Army did not have many people available to them. They always were short handed compared to the British and George Washington never had more then 20,000 troops at his disposal in a battle.
The Continental Army had little supplies to give to their soilders. Without a economic military powerhouse to support their war machine they couldn't hold a fight. Most guns were personal guns from the soilders and not the army.
The American Tresury was very small. With the newly formed articled of confederation the goverement was unable to tax states and therefor had no money for the war. George Washington often complained to the Continental congress about the lack of money but he was not given an answer about it.