It may sound a little daft but when I find putting everything all together overwhelming I tend to practice each element separately a few times before running through a piece as a whole.

An example would be to run through the tab in your head a few times with a metronome running without even touching the guitar. Then maybe do a run through where you are only fretting the notes to the metronome without strumming and then vice versa (picking the correct strings to the click without fretting the notes.) A step further from this would to practice the verse and the chorus in isolation before bringing them together as a whole.

I have been doing this when I get stuck working on a song and it has been helping me a great deal. Hope this helps a little.