Harry Potter: Hogwarts Mystery Cheats for Android

You forgot about the energy you can get from the Golden snitch on the quidditch pitch.

Later on in the game, other areas open up and you can find more energy that takes a bit of time to come back once you get it.
Forbidden Forest - The big spider web in the tree by the Spiders Lair
Magical Creatures Reserve - the gray dog/wolf

You can find extra energy by tapping specific objects in different places at Hogwarts. It will take a little while for them to recharge, but worth picking up +5 energy.
Location: Castle Grounds
If you scroll to the right you will see a large stick on the ground. Click it and Hagrid's dog will get it. Earn +1 energy.
Location: Dungeons
Just to the right of the kitchens you will see Dobby sleeping. Click on him to wake him up and earn +1 energy.
Location: Lower floor (West)
Just outside the Great Hall. Click the right pillar to light flame. Earn +1 energy.
Location: West Towers
To the left of Moaning Myrtle's Restroom there is a painting. Click on it to add fruit to picture. Earn +1 energy.
Location: East Towers
The first painting you see will be black. Click on it for a bride to appear in frame. Earn +1 energy.
This is just what I've found four Year 1. They refresh after a while so you can use them again. 😊