What to expect in Diamond?

So I was really stoked that I was finally promoted to diamond rank a few weeks ago, but the transition has been extremely difficult. I'm only winning about a fifth of the games I play, and I really don't understand what I'm doing. I am weak in all match-ups.

I feel like I'm lacking an understanding of what Diamond level play is supposed to be. So my question to you ATT is this: what should I be doing as a Diamond player? What should I be focusing on and how can I improve? Is it more strategy incorporation now or I should I still be buffing up my mechanics?

I don't really have any replays because this is just more of a general understanding rather than a specific match-up..

Thanks in advance guys. It feels good to be higher ranked but I'm starting to feel like I really shouldn't be in this league.