Check out Valkia on youtube. He has great tips on how to get better at pharah besides the ones already mentioned here. Also watch how pros/streamers play Pharah. That's how i got better. Good luck!
The best tip I ever got was to remember to use the environment. Stay behind stuff. Pop out from other angles. You can fly, don't come at a good hitscan from the same place twice in a row. Your job is to distract, put pressure, and hit the back line if you can.
With pharah just improve your instincts and prediction.... Where the enemy will be in next second..... Btw also use E ability to push people off map... I got potg when I pushed 2 people right at start... Practice and practice