If you find that your solos are stagnating, consider exploring guitar phrasing. As you already know, almost everything on guitar is based on chords or scales. However, with phrasing, your attack (the dynamics) of a musical piece can also have a big impact on your music. Instead of just soloing a memorized riff, the concept of phrasing is to bring out the emotions of your musical ideas.
Below, I’ve written out three phrases that bear the sound of the chords written above the staff. Don’t get hung up on the fine details of exercises, but attempt to make them a natural part of your playing as if you are trying to speak with the guitar. Play the chords, get them in your head, and see if you can express the emotions of those chords within the phrase. I know this may seem abstract (because it is), but the more you attempt to “speak” with the guitar, the more you will start to notice the difference between a riff and a phrase.
In Example 1, the first four notes outline the Gm6 chord. Instead of just jumping into the arpeggio (notes of the chord played individually), I added a grace note before the first beat. This gives a softer, more inflective sound when starting the phrase. I’ve also approached the rhythm with a shuffle feel which, to my ear, gives the whole piece a nice bouncy feel. It is these little inflections that keep the music from sounding mechanical.
Example 2 simply lets the notes ring out and bleed into one another until the third beat. This type of playing can sound sloppy if you’re not careful, so use your best judgment.
Example 3 looks more like a riff than a phrase. I chose to play everything in a legato style (hammer-on and pull-off) throughout, and then used a vibrato on the last note. I personally like to make my phrases sound smooth. Your approach may be different than mine. Maybe try a strong accent on each beat and see what happens. The choices are endless!
Remember, it’s a fine line between a phrase and a riff. The use of grace notes, legato, and rhythm, just to name a few, help develop your personal voice. When and how you use them will not just take your playing to a new level, but will help you in developing your own unique musical style.