What am I supposed to look out for when watching my replays as support?

I could think of these. Prob there's much more that I couldn't think of or that I don't even know about yet.

• Lane dominance 1: not necessarily kills, but how much did you forced the enemy laners to respect you(missing cs, etc.), and how confortable did you made for your adc to safely farm;
• Lane dominance 2: every time any of the enemy laners go missing, ask yourself what you could've take from that. It could be a kill on the other laner, a roaming mid (or following their roaming), shoving the minions and denying gold/xp, taking your time to ward and gain map control, gaining information about their warding (and warning you jungler that the river is warded, for example), etc.;
• Wasted cds: every time you use a skill, it opens up a window of time where you can be all-in'ed with 1 less skill available, try to avoid those situations and/or maximize what you take for every skill used in lane;
• Map awareness: whenever your lane is ganked, rewind 30 seconds before and look for something that would've telegraphed that gank; Whenever the enemy jungler shows in any other lane than yours, pause and ask yourself how you could've took advantage of their absence near your lane, either forcing a trade, an objective, deep warding, etc.;
• Developing your champion: whenever you find yourself using skills, watch for sequencing, taking the enemy's skills in consideration, etc.;

I hope it helps, sry any english mistakes, not my first language. =)

Depends what supp you play, but they usually don't die much and get huge kda's with 20+ assists. I don't main support, Jungle/Mid. When I am mid thought I will play as a support (I'm maining Orianna at the moment). This is what I look at other than the laning part:

• How many deaths do I have. Most of my deaths are just me attempting something crazy, or going into range of enemies. How did I die? Support isn't the role that usually really dies for the team, but rather stays behind and supports the team, unless you are playing champs such as Leona Braum then it is totally different and dying is fine alot of the time. With Orianna I just want to stay behind my team and shield the right guy or whoever is in rage in the worse case and slow/speed up and make 3k elo ults. Janna would be pretty similar with a few exceptions. Nami too, you don't want to spell yourself to dps, but either the adc or frontline.

• Did I help the right guy? If the adc is first time (op.gg OP) and 0/7 with 4 cs/minute and looks like he plays without his hands, you probably want to help him.

• Did I stay positive? Yesterday I had an easy game as Orianna mid (on my smurf though) and I was able to not rage or even care when my jungle and top came steal my farm with 0 pressure, like its normal. This happens alot in low elo (below plat) and drives all dia+ people crazy, it makes me mad af usually. Tilting can rly cost you the game, its just a waste of time and makes people play less good. I could give you examples. It REALLY matters!

• Calls made. You don't see that in replays thought. Didn't check Riot new replay system, they might have this.

• Did I want to force too much things to happen and went in first? This is not good most of the time (except with Thresh Blitz), if your team is really bad and refuses to do the free Nash forcing it won't work. You might end up doing it after 20 minutes of forcing your team, but by then the enemy team respawned and aces your team, game over. Not doing baron at all would have been a waste, but wouldn't make you lose.

Also, for laning as support there's one thing I know that's REALLY hard:

Are you able to give up? Let's say you got free kills, but your adc doesn't want them. Because he's stuck in silver 2 (or whatever) for a GOOD reason. It's super frustrating, but are you able to go into yoga mode and let it slide? Or will you do as I often do and go force anyway and die? This is one of the most anoying thing that makes people want to not support. If your adc that you carried even thought they sucked and proudly told everyone in game how good they were and carried adds you after and wants to duo, you're totally allowed to press no very firmly and download the kind of flash game that consists of smashing some nerd looking guy in the face :>

Probably something like:

Do I zone (enough)? When could I have zoned where I didn't? Do I poke (enough)? When could I have poked where I didn't? How do I behave in trades? Can I do anything better (Retaliate? wrong targets?) Did I miss opportunities to roam? Did my wards give enough vision? Can I place wards at better spots? How did I die? Why did I die there? Could I have prevented it (answer is yes, but how?)

Stuff like that.

There are a few ways to approach replays, but I guess what you're looking for are small lessons that you can apply to future games.

Things like...

1. Skip around to each death and figure out the sequence of events that led to the mistake that caused the death. This helps identify dangerous situations in the future.

2. Watch your movements and make notes about what you should be doing when your champion is otherwise doing nothing. This helps identify lulls in future games where you should realize that you need to keep active. Minimizing time spent doing nothing can be a huge improvement to gameplay, because it should increase your pressure and the amount of wards you place.

3. Watch the enemy lane and identify when you are missing out on free harass. There are always times when the enemy ad carry is clicking on a minion and the enemy support is not ready to trade where you should be taking advantage. Being able to identify these situations quickly in game will greatly increase laning pressure.

Everyone brought up good points, but I feel that one that everyone is forgetting about is proper warding. Observing the enemy's ganking and roam patterns and learning when and where to ward can greatly increase your chance of living and also give your team better chances at macro plays.

You can't learn much from your own replays. You learn from watching someone better doing things. But you can spot your mistakes in your replay and look at challenger streamers and see how they handle it.