Always observe the local area

Running between buildings can be tempting, as it gives you the chance to get your favorite weapons or high-level armor and helmet that make the gameplay much easier. However, any such action increases the chance that other player (who's currently hiding somewhere in the vicinity) may suddenly jump out and open fire. Before you get to a new building a few dozen yards (or meters) away, take a few seconds to quickly explore the area. Pay attention to the movement of nearby players and whether anyone has just run into the building next door.
Monitor the sounds in the area
Sounds and noises, and their proper use in Garena Free Fire is as important as shooting skills or the ability of obtaining useful equipment. Noises will allow you to locate nearby players more easily and prepare for a battle with them. While traveling through the map it is worth to move in crouched position and listen to the movement and actions of other players. Use headphones while playing - even the cheapest simplest headphones will let you determine which direction the sound is coming from, and that is almost impossible when you're using standard smartphone / tablet speakers.
Note - remember that other players will also try to locate you by hearing any noises, so try to move quietly and shoot only when it's necessary.
Use viewpoints

The game is full of various hills, high buildings or observation towers. Climbing to the top of the mountain will give you a great view of the surrounding area. There you will surely see at least a few other players. However, remember that being on a hill is exposing you to enemy attacks, as your character will be perfectly visible to all opponents.
Retreat if necessary
If the battle with another player is not going your way - maybe because he/she is better at aiming or has better equipment, then it's worth to retreat and wait for your enemy. There is a good chance that a player, tempted by the prospect of getting an easy frag, will chase you and bump in right at your weapon's sight. Reduction of the distance to your enemy may be very helpful and work wonders as it will let you shoot at your opponent in a more effective way.