Tips/Advice for a Playthrough of Pokemon FireRed/LeafGreen?

Question

A thread for posting (spoiler-free) advice for a playthrough of the given game which will help anyone playing it. The aim of this thread is to make playthroughs easier for someone who is playing it for the first time.

A couple of rules:

1. Don't give advice for Pokemon as a whole. Seperate thread for that can be found here.
2. Try to keep advice beginner friendly. Do not go into the more complex mechanics.
3. Don't post multiple answers. Edit your existing answers to add more.
4. No repetition

Answer 1

• On Route 25, there's a Secret Power TM normally locked behind a cut tree and a camper boy. This TM can be quite useful earlier in the game, especially if you're using mons like Fearow or Pidgeot that can't get better Normal moves this early otherwise. You can actually get said TM before getting Cut by getting the camper to move out of the way. To do that, all you need to do is to enter the Camper's line of sight, while being at least 2 tiles away from him. This shouldn't be too difficult to pull off, but you can always just save beforehand and reset in case you mess up. (Note: This trick also works in RBY and LGPE to get the Seismic Toss and Thunder Wave TMs, respectively)