Practice does NOT make perfect
No one is perfect and no one will ever be. For Christians, we believe Romans 3:10 that clearly states that none is righteous. As humans, we can practice all we want (basketball, soccer, cooking, etc) and we will still make mistakes every now and then. Our spiritual cleanliness that makes us pure in God's eyes is His Grace that we received from the blood of His son.
In reality, as humans, you can never be perfect. You can only get better both physically and spiritually. You can make progress in life at something if you keep practicing it. The progress may be small or big but you will make progress. So stop thinking you can and will be perfect at anything. Start thinking about making positive progress. From now on, when you hear someone tell you "practice makes perfect," tell them life is not perfect and your goal is to keep making positive progress.
"Practice Makes Progress" - Abraham Inetianbor