As a former Fizz main I've done pretty bad on fizz since i came back 3 weeks ago, snowballed my lane maybe only once. He's totally different then he used to be. His engage now in lane is Q+aa+W or E+aa+W+Q and it used to be Q+W+aa. his teamfight potentional is very bad now compared what it used to be when i played LoL. without flask and 4 pots it's really hard to lane so i take corrupting potion and on first back i buy seal and 1 dorans ring and only focus on farming.
But i said that i'm a former fizz main because i actually switched to Vayne top now and on mid lane i play LeBlanc.
i used to play irelia and akali too but they both got changed.
Only good thing is because i was only level 30 when i came back so people were underestimating me so i managed to snowball few games. Enemy had no idea that he plays against a guy that has 4k hours of LoL and it's been playing since season 1.
Also this champ mastery, i have no idea what that is or how to get it.
About new runes, i use websites and just copy runes from there for my champ.