re: Better Miters

You are learning fast. This looks much better. I think your glue may be too thick. Just a guess but it is the most common “rookie” mistake and you speak of using too much and having bubbles and ripples, both indications that you may have it too thick. Try to iron out the bubbles and ripples after the glue has cooled. If they are just air you may be OK but if they are full of glue that comes out of the cracks when you iron, then you likely have too much glue in there and that is likely because it is too thick.
If your knife is wandering, try more strokes with less pressure. Patience is a virtue here. Don’t be too hard on yourself either. This is not simple hammer veneering you are doing. It takes time to get all the nuances right.
You’re doing great!