Every character that can be used in real time strategy games are different. Normally, no player can use the same character and this makes the game more fun because of the variations of skills and capabilities of each character. In the League of Legends, Garen is one of the favorites of most people because he is one of the most powerful characters in the game. A lot of people are trying to figure out how to use him effectively but it ultimately depends on the team and what Garen will be used for in the game. Garen can be used offensively or defensively and because of this, he makes a great addition to any team because of his versatility.
Offensively, the skill that will be upgraded first should either be Decisive Strike or Judgement. This depends on who Garen is with or if he is fighting alone. If the companion character of Garen is able to immobilize the enemy, then Judgement should be upgraded more so that Garen can deal more damage and kill the enemy quickly. It is a great skill to use because it has an area of effect which means that even if there are two enemies, they will both get damaged as long as they are within the range. If Garen is with a character that is able to deal more damage than him, Decisive Strike is the best bet because it will silence the enemy which will prevent him from casting spells that might counter your attempt to kill the enemy. Judgement should always be ahead of Decisive Strike to be able to deal more damage. You can upgrade Decisive Strike just once in the game and you will be fine because the silence stays the same at 2.5 seconds. Upgrading Courage once will also help Garen too as it will let him take much less damage which will make him harder to kill.
Defensively, Garen’s Courage skill should be the primary skill that should be upgraded because it allows Garen to protect himself with increased armor and magic resistance which is important to take on the damage that the enemy does. Along with an upgrade of Perseverance, as long as the hp of Garen does not go below 50%, there is nothing to worry about. But if the hp of Garen is less than 50%, make sure that you have potions to use because having a low hp will kill Garen if the enemy has early game killing skills especially spell casters. A combo will kill Garen right away which will make Perseverance useless.
Upgrading Decisive Strike at least once and going Judgement and Courage all the way is how most people play Garen for offensive use. For defense, Perseverance, Courage and Decisive Strike are the first few skills that they will use. You can always mix it up a bit though depending on your opponents. If all the enemy characters have low hp like spell casters, you can just use Judgement and Courage and it will be very easy for you to pawn them because of the additional magic resistance which will make their spells less effective.