Remember: Your E is a key to kill someone, but in another way is a key to escape, so if you want to go for trade, remember to be in a safe spot/have vision.

VS ranged: If you can get close to ennemy without any problems just play more agressive, but if you can't, play safe and wait for a gank. And remember, use your passive much as you can.
VS melee: If they're not champions like yasuo, yone or sylas (lethal tempo/sylas W) you can get very well trade.

When you are playing phase rush, remember just to prox it and then run (obviously if they are low that you can just end them, do it).

Remember to cancel dashes like Akali's E, Yasuo's E, Fizz's Q etc.

Gragas E is very good to cancel skills that are charging like: Sion's Q, Nunu's R or Zac's E.

The most important items that you need to have is: Lost Chapter(For Luden/Liandry's/Everfrost) and Hextech Alternator(For Protobelt/Shadowflame)

Remember that if you can't get any value from staying on mid/top (can't get farm), just roam.