Ok, So my guitar teacher recommended a metronome to increase my rhythm playing, I know scales so what I do is set a metronome at 90, and every beat I would go through a major or minor scale doing an down stroke on one note, and up to the next note, as each beat on the metronome clicks, is this a good way to increase my rhythm, also I am confused on using a metronome in a song.
Your metronome acts as a drum beat. Use the clicks as a guide!
Playing with a metronome really helped shape my playing. Here is a guide to what I do when warming up... hope it helps!
Pick a scale; I like to use E natural minor or E harmonic minor to warm up with.
Set a tempo, for warming up I set it 120bpm.
Play the scale up the whole neck playing one note a click. It's quite tedious, but if you can't play tight at slow tempos then don't try playing fast!
Play the whole scale up the neck playing two notes a click
Then three, then four, then six, going up and down the scale.

Hope this helps!
^ is the same method i use, except if you want to get a little bit more crazy, try doing EVERY different note count per beat, i mean 5s, 7s,8s, 9s etc... makes you want to shoot yourself but is very helpful
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