With midlane, the point of what champions are chosen for midlane is based on the close proximity of your tower, and therefore safety. Squishy champions with long range and mobility like the lane for the ease they can reach safety from ganks. As mid is the most gank vulnerable lane, this is pretty important for them and for a midlaner to take advantage of. It is of course also the lane with the best map presence, able to roam and gank on its own.
For a few straight up tips:
Know the enemy jungler and the probability of when they'll be trying to gank you. Eg. Warwick probably won't bother you until he's level 6 but Shaco will show up in your lane at level 2 with red buff.
If you're going to leave the safety of your tower, ward one side and stay on it. Maximize the vision you have for incoming ganks.
Most matchups have you either standing in the corner of the lanes (against passthrough skill champions) or in the center of your wave (against skillshots that hit the first target)
Waveclear has several uses for midlaners. It can neutralize a losing lane. It can shove a lane quickly before you roam, to disguise you leaving.
An early pink ward makes life much easier. It's usually best in the bushes near the river on your blue buff side, but if you choose to place it in the lane bushes, keep it as close to yourself as possible.
There are a lot of aggressive players mid. It takes practice surviving them, but as you get better they start to only become jungle bait. They get aggressive, they push the lane, and then they get ganked.
Don't go roaming just to go roaming. Your jungle really should be the first person on your team ganking. Farming your lane has a lot of value in its own right. Rather, you go gank side lines when the opportunities line up. Top is pushed, my ult is up, our top is able to help, I can leave mid while disguising my intent. Okay. But even just getting seen by a ward along the way makes it a waste of time while your opponent gets to shove your tower. You can also do things like clear jungle creeps and place deep wards when your minions are away from your tower.