First ask yourself..
What are my strong points?
What are my weak points?
Am I understanding what I watch in videos?
What kind of videos do I watch?
Do I put what I learn into practice each game?
What kind of tips can I learn from more experienced players?
How is my...
Map awareness?
Warding skills?
Mechanics?
Creep score count at 10 minutes?
Rotations?
Roaming?
Positioning?
Mechanics wise can i..
Orb walk?
Hit skill shots?
Pull off my combo correctly?
Use active items to the best of their abilities?
Use my summoned spells at the correct time?
Am I....
Dieing too much?
Raging at my team too much?
Not pinging the map for my team?
Helping my team?
I could go on but there's just soooooo much and I can't think of it all at the moment. But this is just some food for thought that you need to ask yourself. No one can give you a miracle sentence to magically make you a better player. What you need to do now...
Is play the game.