Wassup man,
Listen, keep in mind that this talent you have was given to you from the Lord. In order for you to get better you have to take in the advice of all the people above, they pretty much hit the nail on the head. Its a spiritual and natural thing. Naturally you need to practice as much as you can, learn from seasoned musicians, listen to songs and try to learn them, do what ever you can to get better. Spiritually you just need to stay in God's face, not really about increasing your playing ability, but just for who He is. Why? Because God already know what you are in need of!!!! Guess what, He will increase your playing in due season, but the word does say that faith with out works is DEAD which is why you should continue to practice (naturally) Practice, pray, seek God's face, live the life you play ( or sing) and everything else will line up. Remember: Seek ye first the KINGDOM, and all that other stuff is gonna be added. You are already in a blessed position because God choose you do play and or sing anyway. Trust me I know. I am praise and worship leader at the ministry I attend, and I learned that as long as the anointing is present, and you are able to tune in to what the spirit of God is saying and or commanding then you are on your way to great things!!! Stay encouraged, Keep playing, Don't focus so much on playing extra tight, If you are anointed then your in there!!!!!