Watch the opponent's cooldowns, especially if they are a Mage. If they use an ability to CS, they are one ability short in any upcoming fight for the next few seconds. Especially in a lane where abilities are almost everything, this is gigantic in a fight. Stand off to the side, watch how the enemy moves and positions, and Shunpo them the moment they farm. You can take this a step further depending on the ability. Timed right, you can dodge many Mid Laner's skillshot abilities simply by Shunpo'ing to them as they're using their ability even if they are aiming at you.
I recommend you just keep playing Mid Lane, and get familiar with everything. Have a secondary champion to fill out your role (aka, try picking up a Mage some time), and keep analyzing different Mid Laners. Notice how some solve their problems in different ways (Mages tend to aim for control, Assassins tend to aim for opportunity). Have a general-ish idea of when certain champions naturally power spike and which of their abilities is most important to them. Assassins like Katarina take good advantage of general knowledge of Mid Lane since if you know when most of your matchups are strong or weak, you open up so many opportunities for yourself.
I also recommend you expand outside Mid Lane once you are confident in yourself to win lane on your own. Don't worry about that now - focus on your Mid Lane skills if you want - but you're going to want more general game knowledge from all the roles to round yourself out in the future.