When it comes to power leveling, nothing else worked better for me than just going around killing mobs 1 – 2 levels higher than your character. Questing would probably benefit you the most in the beginning, up to about level 15, but after that, its better to just go around and kill mobs. While you do get a good chunk of experience for turning in quests, the amount of time used to perform the quests as well as the time it takes to travel could be better used to kill enemies. Picking up various quests in WotLK can help you since the experience rewards are pretty big for doing very little, but mob killing is still the way to go. Instance grinding also helps level pretty quickly as the mobs yield a lot of experience. Unfortunatly you need a group for that kind of activity. Instance power-leveling is the best I believe. There are several ways to power level, but mathematically, only killing mobs and not doing quests will help you level faster because it gives you more experience per minute
If you mean the fastest way I can recommend to buy leveling on special service like https://boosthive.eu/wow/leveling. It has many advantages, such as: you can boost your level considerably in a short period of time, you can get new exclusive armor, weapon ability or whatever the game has to offer to its loyal player, you can earn more money and rewards, and many other.
To play more maybe. That’s way you are making your level on and you are developing your game. I was thinking about playing online games and stopped at http://iospace.games/agario which I can play even when I am having some break. Just a quick and amazing game for several minutes.
Usually, when I need to level up my hero in WoW, I turn to Rocketboost https://rocketboost.gg/en/30-world-of-warcraft-boost for help, as I know that they work reliably and do not use cheats, so my account will not be banned. Also, there are adequate prices and ready-made results, I always get it on time. And then finally I can safely enjoy the game for my own pleasure, without unnecessary nerves and wasted time.