PSA: If you died early, play safe.
If you died early, it means your enemy is probably 2 levels ahead of you, half of a item ahead of you, and having higher stat than you. A lot of people in my elo don't seem to understand how to play safe, so I wrote this post to help people in my Elo.
what you should do is: 1.Avoid any kind of trade 2.Only go for last hit when enemy is not in position to take advantage of it, value of 1 cs<1/4 of your hp gone. 3.Ward, when you are weak you might seem like a easy gank to the enemy jg. 4.Build defensively, don't listen to any of the "semi-defensive" bullshit when you are behind, any armor/mr early game makes a huge difference. 5.Don't push the wave unless the enemy backed, pushing the wave will put you far from the safe zone(your tower). 6.If enemy team tried to tower dive ask for help from your teammate, if they aren't in position to help you then back off to your second tower. Since you probably won't survive the tower dive why not just give up the tower because they can still take it after killing you anyways.
What you shouldn't do is:
1.Go for poke/harass/trade: wasting the cd of any of your ability on unnecessary trade will result in your disadvantage.
2.Overextend: your enemy might let you push a wave or two for free, they just want you far away from the tower, don't take the bait.
3.Build full dmg: unless you are some extreme cases(
) where building defensive items are just flat out meaningless, you shouldn't go for full dmg items because your enemy will for sure out damage you.
are good semi defensive items to get.
4.Don't redo what you did before that caused your death: either tower diving, taking too much minion agro, not warding, over commit when enemy has ignite and u dont, etc. If this caused your death last time repeating it will only cause another
5. leaving it blank for now.
Feel free to add more tips in the comment.
No, go fuck yourself.
FOR THE CAUSE! 
Adapt
Grow
Evolve
Win