whatever guns/builds you are using, look up some guides. i know, i hated the thought as well. but switching just a few things around (mods, weapons, class, etc), you should find things get much easier. it's super easy to get stuck into using a 'build' you enjoy and are used to, but the 'new' systems encourage build crafting to almost force you out of your comfort zone/playstyle. but usually it's not that big of a change and soon you should be finding it much easier to work through that content you are currently struggling with.