Here is a list of skills that are essential to be good in TFT. Each of these contribute to winning a game, but are not weighted equally. The more of these you master and consistently apply, the better you will be at TFT, which will affect your ELO and rank. If you do not know what to improve on, take a look at this list and pick out one skill at a time to truly master.
More guides to elaborate on each of these skills to come!
Skills
Positioning
Scouting
Economy Management: https://youtu.be/uCOBkRDk308
Team Strength Assessment
Rolling Abilities
Adaptation
Draw Optimization
Composition Pool
Mindset
Win Conditions
Streak Management
Power Spikes
Itemization
Reading the Lobby
Game Mechanic Abuse
Meta
Ping
Composition Matchup Knowledge
Champion Knowledge
Carousel
Early Game
Mid Game
Late Game