Umm start out with tanks. Shen, Rammus, Amumu, Leona, Malphite, Maokai, Taric, Galio.
They have more sustainability and it's just easier to not die with them.
Always get your ult(R) at lvl 6, 11 and 16.
If you have any left over gold buy Sight Wards from the consumables section in the shop. Use them in the river brush and at key points like Red Buff, Blue Buff, Dragon and Baron. Do not solo Baron.
Don't get the Promote summoner spell. Or Revive.
Don't buy Runes until you've unlocked Tier 3.
Don't use Evelynn.
Look up builds and guides for your character at solomid.net
Don't leave mid game.
Don't ever apply a negative attitude ingame otherwise you will bring your team down.
Mordekaiser es numero uno.