Hi there!

I'll keep this as short as possible so you're not bored to death :)
I have been playing LoL since around halfway through Season 4. I reached level 30 and did my placement games around September/October 2014 and placed Silver 2. I was then encouraged to duo with some people that I shouldn't have and ended up being demoted to Silver 5. Then pre-season came around and was told pre-season ranked matches had no impact on Season 5, so I played ranked like they were normals. I then did my placements at the start of Season 5 and placed Bronze 5 due to being demoted to Bronze 2 in pre-season.
I am still fighting my way out of bronze with a 50% win rate, which considering the short time I have played in comparison to other player, I don't think is overly too bad.
I do still have a lot of learning to do obviously but I do have certain champs that I play frequently and know very well.

If you made it to the end then thank you :) If not then thank you for trying.

You will be trying to avoid enemy abilities that you know will hurt if they hit you, by simply hopping up on your stick, that then gives you an opening to attack (if you have good hp).
I can usually get a kill before reaching level 4 by simply poking the enemy when they get close to farm or attack you, don't be afraid to poke, you're a Fizz!
When they are around half hp or less, I use E to slow them and then activate W and then Q the enemy to keep up and land a few auto attacks before hitting ignite and hearing "First Blood".

When you hit level 6 this makes it easier for you to get a kill as your ult slows the enemy. So let the enemy push you towards your turret, throw your ult under their feet and they will instantly turn and run, thus giving you the chance to activate W and Q to them to land as many auto attacks as possible. If they are about to get away with low hp, hit ignite.

Ward whenever you can to prevent ganks as they will focus you if you get early kills.
If you're ahead but just need to earn gold faster then buy Avarice Blade as the gold income from that is incredible and it gives you crit chance too which will help slightly, then sell it when you want/need.
When you are a good 2-3 kills up then look at other lanes that could use help. Try to let the laners get the kills so they get fed. This helps your laners greatly and it really helps your jungler as they can then either gank another lane, or stay in jungle longer to farm for items and xp.

When it comes to team fights always remember who you are, you're Fizz who is an assassin. You're not meant to stand in the middle of 5 enemies brawling it out, you are an in-damage-out champion. With this build you will be able to do alot of damage in a very short space of time.

When you have your team with you in a fight, throw your ult at an enemy trying to escape and let your team take them if they can, then you can focus another enemy which brings their team down to 3 champs alive allowing your team to get the ace and proceed for an objective.