Practice practice practice. The sound will come later. Do finger drills and major and minor scales up and down the nevt of the guitar. Over and over and over. Pick a couple of songs, simple 3 - 5 chords. Write down the lyrics and chord changes. Play them over and over and over and sing them the best you can. Any old blues songs are great. There’s a thing called 16 bar blues progression. Practically every blue song and a ton of rock songs follow this pattern, 1-4-5, eg A,D,E. Make’m 7ths. Within a month or so, bust out your guitar and play and sing for someone. Btw, blues are the absolute best for learning to improvise. You can hardly find a wrong note. Learn to play and sing Boom Boom by John Lee Hooker. E,A7,B7…just strum these chords, don’t worry about the licks. In no time at all, you’ll be rocking out. Your reward is to get to share your work with someone and think of it as a gift to them. Now get to work. Consistency is everything!