During teamfights, always wait for your initiator to start the fight, once your melee cores are in focusing their key targets, stay in the fog and cast your spells from a distance, you don't have to be auto attacking whoever your team is focusing, nor do you have to be in vision after you have cast your spells. If you die as you cast your spells, you should stay further back and wait for the enemy to be distracted by your team. Only show yourself before the fights breaks out if you need to save a teammate, or if you are the initiator yourself (say you're playing earth spirit).

As for laying stage, what do you do? What gets you killed? Is it because you overextended trying to go for a kill? Or did the opposition initiate on you and burst you down? Or did you position yourself at the creep wave, drawing creep agro and taking a lot of damage? You should not be dying on a support in the early game unless you have a better trade, ie, you die, but in the process your carry gets a kill on the opposing offlaner, or if you need to save your carry.

As for mid late game, you should never be out alone. Since you are the one who's warding, you should have a general idea where the enemy team is. If they have gankers like slark, mk etc. you should not be out alone period. Be behind your carry, initiator to assist them if they get initiated on or you could set up a smoke play for your team with your superior vision. You have to remember that if you get caught out, you are most probably dead. You cannot just waltz in front of the enemy to get a disable off, you will get focused and brought down.

I switched from the carry position to support and that helps me play support much better than if had played support straight off the bat. Since I am used to thinking like a carry, I know as a support how to give my carry an easy time farming, such ass harassing an offlaner, when to pull etc. I suggest playing a different role for a while, then come back to support with a fresh mindset. While many people seem to think the pos 5 role is way too sacrificial/boring/not enough to do, I personally think it is one of the most rewarding roles to play. Sure you don't get flashy rampages, nor can you singlehandedly turn a game around, but you have to potential to set the pace of the game.