Practicing at a slow tempo can yield great results to your playing. It’s all about taking the guitar lick, or riff you’re trying to get good at and slowing it down. Try slowing it down on Youtube or a software application that slows the music down.
To do this properly you’ll need to know how to play at a slow tempo. This means you need to learn how to play the lick or riff in time with a metronome, which in turn requires you to understand time values with a beat, counting relating to those time values and time signatures.
Try slowing down one of the Tux Guitar files in the Guitarealm course exercises - here - slow it down to a tempo you feel you could learn to keep up with and practice it without making any mistakes. Keep doing this daily and you’ll start to notice a gradual increase in your ability to increase the tempo.