Top Secret Guitar Tip!
If you are learning to improvise in a genre (blues, old-time rock n roll, southern rock, metal, bluegrass, jazz, gypsy jazz, swing, bebop, country), learning a couple licks is the secret to sounding like you belong. You don't just have to endlessly explore and hope that you'll find something that sounds bluesy. Learn a lick. Play it in a song.
Licks are like regional vocabulary. If you visit the south, you might just find yourself saying "Y'all." It makes you sound like you're from there. If you go to Boston, you might start saying "pak the cah."
Licks are the same way. If you play a Tony Rice lick, for those two measures, you sound like Tony Rice. If you play a Stevie Ray Vaughn lick, you are a blues master for a few seconds. Who else? Maybe Van Halen? B.B. King? David Grier? Clapton? John Mayer? Charlie Parker? Chuck Berry? Brad Paisley? Their licks are the gateway to their style.
What style are you learning? Blues? Learn a B.B. King lick, and play it in every song until people tell you to stop (then keep playing it)! Jazz? Learn a cool Charlie Parker riff on guitar, and find a place to use it. Bluegrass? How about a Doc Watson lick?
Licks are always associated with chords. G licks go with a G chord. C licks go with C chords. Some licks go with more than one chord. If you know a lick over a G chord, and the song you're playing has a G chord in it, try throwing it in.
You'll have more to learn but you'll sound like you belong. Remember there is no ONE answer to the question, "How do you improvise." This is just one step in the journey.