For me, the easiest way to create the mood of the beat is to lay down the chord progression of the loop first.
You can add drums and bass on top of it, but the chord progression laid on the beat will ultimately determine the mood of the beat.
If you want the chord progression to be more subtle, you can either put filter on the instrument, and/or change the instrument to something like pads to make it more atmospheric., and/or lower the volume of the track.
How do you find the chord progression of a song?
That is, either do it by trial and error, or use the Internet to search for the chord progression of a known song, or use apps like Yamaha Chord Tracker to analyze the chord progression of the song you have in your iPhone.
Try it out!