Heli size does not matter, basics are basics for all sizes. 450 should make it easier vs smaller ones. Heli's larger than 450's give even more stability and "float" for more time to think and make corrections.
Learn all orientations up right and inverted.
Learn circles in all directions and orientations.
Be able to flip and roll the heli towards you, away, from all sides nose down and nose up in control.
Piro - left and right with cyclic corrections to hold position, start inverted too.
3D will expand from there, a few good starting points:
Rainbows are a great start, elevator and aileron and can be worked on as your perfecting the basics.
Piro's - move from stationary piro's to controlled piro movement - circles, back and forth, down runway, etc.
Funnels - a natural progression from circles
CAUTION - my posts are based on my experiences, yours may be different.