A certain combination of skulls will help a lot, like the "Grunt Birthday Skull" (if you have it, not everyone does) and "Boom" are useful, but there's a cheap and efficient way to do this as well without stressing over dying over and over again.
You can simply turn on another controller and sign them in. No one has to be playing, but A. It's useful in case you die with an important weapon (IE. Sniper on the Truth and Reconciliation level), then the other player will also have this and you can use it twice. B. You can have an easy spawn point in case things get bad. Just be sure that you placed the character you're not using in a safe spot for spawning.