As requested by ~Chinky-chan. Hope you find this helpful in some way!
PLEASE BE REMINDED THAT THESE TIPS ARE MERELY SUGGESTIONS. BE ADVENTUROUS!
I've done a handful of tutorials in the past over at my old account, ~twisted666. They're grossly outdated, I know, but I don't think I'll be taking them down in case some people might still find them useful.
Anyway, while I'm on summer vacation and going through burn out, I have some time to spare. If you have ideas / suggestions for a new Very Concise Tutorial, feel free to PM me.
No particular reason, you can use one method or many methods at once -- it's your choice. But for the stamp, you can cover a big area at one go. This method is especially good for mood backgrounds, I think. It's more location-oriented than using the Fill tool, if you know what I mean.
Honestly, I think there must be more ways of toning that I'm forgetting or don't know about. I just laid out some simple methods that you might use interchangeably. I'm glad I could help! You're doing really great!
And, OMG, I just noticed that you're from the Philippines. *fail* Kababayan!