Flight training can start with simple step-up. You step back & change the word command to 'Come' - getting further & further away [you can start with a clipped bird as they still can fly some]. Training is more focused

if done before meals & food is offered as a reward. You don't train for very long each time but you can train a few times a day if you want. I have only progressed to the 1) come to me across the room, 2) from another room where he can't see me & 3) flying down to me from 'the light fixture'. I have been pretty slack with it over the past 6 months & still he does the stuff he learned. Laker progressed really fast last December when i started it & he was a mature bird so you don't have to worry if you don't have a young bird. One other tip would be - make sure they are focused on you before you give any command - otherwise you could train them to ignore you or not take you seriously. [ if Laker is chewing his treat - don't give too much treat or you wait longer - he will not come]
2nd bird - & I also cage Laker & put him outside or in another room to focus Rio & work with him in a closed room so he doesn't go off to find Laker.
Note: we have to keep the lights off in the ceiling lights until we buy a covered light fixture - we live in an apartment & those cheap light fixture covers are irresistible for the Budgies. I don't want them hurt by hot light bulbs or broken glass.
To stop indoor collisions - I suggest landing perches, gyms or shelves near windows & mirrors - they are more inclined to land on something to check it out. This has worked for me. When i first let Laker out of his cage i sat down - not wanting him to be spooked by my movements - he was very calm.

I loved the leaf motif - will look around for it - there's a wild bird store near here & they're sure to have it - hopefully.
Great thread,