If you learn how to kill Bastion and Torbjorn without yourself dying, it doesn't matter how rubbish you are at any other aspects of the game, people will love you. :)More seriously, those two and Pharah are really good for starters. Bastion's entire schtick is planting himself in one place and simply aiming and firing, which gives you a chance to figure out the pace of the game without actually being required to jump around and use the terrain. Torbjorn's big thing is placing turrets, which is substantially kinda the same thing, plus he has a shotgun.
Pharah can fly(ish) and has a rocket launcher. That gives you an "oh fuck oh fuck oh geez GOODBYE I AM LEAVING NOW" button to push if things get nuts, and doesn't actually require you to have amazing aim in order to have a good chance of murdering someone. Her ultimate is also AOE, which, again, means you don't need amazing skills in order to rack up a few Play of the Game headlines: you just point yourself at a crowded courtyard and hit your button.
Mercy is also a decent choice if you want to stand back a little and not get stuck in. Her healing skills don't require you to be right on the front lines. She often has a pretty big target on her head, because she's Mercy and has a tendency to do shit like "Ha ha, you thought you killed Genji and Reaper, that's adorable," but your team will, if they're at all competent, move heaven and earth to defend you, and people tend to really fixate on Mercy. I've seen more than one idiot get his damn head shot off because Mercy disengaged and ducked inside a building, and their foe ran right past McCree or Tracer or someone in their lust to kill the healer.
If you're bad at aiming but good at reading game flow, Mei is a good choice. She has a very, very high skill cap, but using her ice walls properly can damn near win a match single-handedly.
Do not start with Tracer. Tracer's power and moveset depend on you being able to keep yourself oriented after repeated teleports and make split-second decisions about when to reverse time. If you don't have superb situational awareness what's going to happen is you'll charge into fights, get in close (because your pistols are short-range) and then Reinhardt caves your head in with his hammer because you got tunnel vision and didn't notice him walk up on your left.
Speaking of whom, Reinhardt is the best starter tank. His powers are easy to use and very, very satisfying when you score a kill with them. If you can get on top of an objective you're pushing, either a capture point or a package, and have a healer in your back pocket, even a good team is going to have a bit of trouble dislodging you. Keep your shield up if you suspect Widowmaker and Hanzo are around; Reinhardt has a big old noggin that sometimes seems to have a bullet magnet in it.
Hanzo is the best sniper in the game from a standpoint of pure damage output and ability to put people on the ground in a single hit. Widowmaker is far easier to use and if you're on a proper team with everybody using their voice chat like they're fucking supposed to her wallhack vision is probably superior, because you can call out things like "Reaper just teleported past you lot" and suchly.
-Merc
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