With fizz, you can take advantage of his ability to enter and exit a fight with practically no damage, thanks to his abilities. Keep in mind that, if you play it as an assassin, it will not resist many blows, therefore, once you have entered the battle and have deployed all your skills, on non-defensive targets of course (unless you buy magic penetration, that if there are many tanks I recommend), use zhonya to be invulnerable and, once this effect is finished, use your e or your q on enemy minions to escape, for that it is necessary some cooldown reduction. If you are in individual line, in the first levels before the teamfight, raise first your w, then the e and then the q. At level 1, since you will have the w, dedicate yourself to farming without taking much damage, until at level 2, with your e, you enter battle, normally it is played against non-resistant mages, and fizz is quite resistant in terms of initial magic resistance Therefore, it would have no problem and you can cause a lot of damage, damage the opponent repeatedly and you can even draw the first blood. When you are level 6, taking advantage of the passive of your ulti, before entering the battle, use this one, get closer with e (try to make sure that the impact of the e will hit the enemy, and if you can, take advantage of that slowdown to prevent the enemy from escape, that is, the e has two parts, the first jump and the second, if you do not activate the second, the distance jumped is less, but the impact is greater and you inflict slowdown, but if you activate the second, the impact is less and not there is slowing down.) then fight w and q. It is essential to have the zhonya available if you want to go into battle in case an enemy comes or things go bad for you, unless you are sure that you can fight the enemy without problem, luck and practice!