Honestly...it depends on what you're struggling with. Do you feed because of the enemy jungler's ganks? Or do you feed because you misplay? You have to start there first. If it's primarily because of the jungler, then you just need to get deep vision so that you have more than 2 seconds to back up before you get gray-screened. If it's because of misplays vs tough matchups, honestly, missing CS is your best bet.
You have to learn when to go up to CS, when the opponent is on cooldowns for abilities you know will hurt you significantly. Missing CS early game while not dying is definitely better than getting a few more CS by being greedy and then giving your opposing laner kills in return.
You'll always lose games, it's statistically impossible to win every single game you play. Feeding is also bound to happen. Everybody has a bad game now and then. But the way to reduce the amount of feeding is definitely just playing smart and to your strengths.