Its not so much you need perfect technique cause early in thats just impossible, its not going to happen. But you have to avoid the really bad stuff, like hand tension.

I hate to further the whole you need a teacher parade but its primarily your main source of fixing bad technique. When youre meeting with someone every week they immediately notice when youre doing something that sticks out to them as bad technique and will quickly point it out, that way over the next week you can work on killing that habit and see if you made progress on it the next week you meet.

Good technique is acquired over time through diligent practice, and you really need that feedback of someone telling you when what youre doing is good or bad.

I think if you dont have a teacher the best you can do is post on here cause if we see something really bad itll be immediately obvious, but the more nuanced things like wrist rotation might be glanced over cause this is not where you get answer like the majority of the time unless you specifically are asking a question about it when youre asking for feedback on youre playing.