The Thought “It’s All Just Luck”
The most common excuse many players give after every loss is blaming it on “luck,” like saying Player A or Player B was lucky to get 3-star champions, while I’m just unfortunate, so it’s only natural for me to lose. It’s true that luck plays a part in Teamfight Tactics, but the careful calculations and reasonable team compositions made by the players are the decisive factors in determining who wins and who loses.

Even rolling for 3-star champions is not solely a matter of luck; some players have even found ways to increase the chances of getting the champions they need (you can find details HERE). This means that to win, you need to understand the game as much as possible; if you only shrug and blame chance without honing your skills, climbing ranks becomes an impossible dream.
Rolling Just for Fun
Rolling or refreshing the shop is an action that anyone who plays Teamfight Tactics does, from Iron to Challenger. However, how and when to roll is an art, and it’s a skill that differentiates the skilled players from the novices. Many players focus on rolling without considering whether they should or not; spending 2 gold and what they will receive may or may not be worth it.

2 gold may seem small, but rolling without calculation will cause your money to dwindle uncontrollably. Teamfight Tactics is a game of resource management; if you can’t manage your money and just roll continuously to get 3-stars, even if you succeed, it won’t guarantee your victory.
Only Playing One Team Composition
It’s true that each season of Teamfight Tactics will feature a few extremely strong team compositions that outshine the rest. However, Riot Games always finds ways to reduce the power of those dominant team comps and buff the weaker compositions to balance the game and create excitement. If players only focus on playing one team comp match after match, it will be difficult to climb ranks; when it’s hot, everyone plays it, and when you’re not contested, it’s too weak.

The meta is always changing; currently, each day brings a new composition that players create to keep the game from becoming stale, and to avoid overlapping with the current strong teams. Playing according to what you have is the most effective approach at the moment, while just playing one composition will only be effective for a short time, making it impossible to climb ranks consistently.
Not Observing Opponents
Although each player has their own battlefield, the secret to winning in Teamfight Tactics is to observe opponents and come up with counter strategies. Remember that “luck-based chess” is still a branch of League of Legends; to win, you have to interact, specifically counter, with your opponents and can’t just play solo throughout the match and expect to win.

Observing the enemy has many advantages, such as seeing how opponents arrange their team, what team they are playing, and how much gold they have left… This way, you can find the best way to counter their strategies; this skill is particularly important in the late game when counter items like the Infinity Edge are essential.