First off, let me just say this -- practicing should be fun! If it isn't fun for you you're probably approaching it in the wrong way.
Here are some examples of bad practice habits:
- Attempting something that is beyond your current level of technical ability or understanding. In this day of freely available tablature and video lessons, it is easy to fall into the trap of trying to play something that is beyond you.
- Spending too much time on mindless scale practice. If all you practice are scales, guess what's going to come out when you play? Scales are necessary for building technique but there's no point spending, say, more than 45 minutes a day on it. Technique needs time to develop gradually and forcing in more hours just makes one a scale robot.
- Trying to focus on too many topics at one go. Instead, pick one topic per practice session, set the goal that you want to accomplish and work at it. Make it an attainable goal so that you finish the session with having actually accomplished something.
- Map out the major and minor scales in all 5 positions vertically in position and then learn to connect the positions to each other horizontally. I would start in the key of C/Am and then gradually progress through all the other keys, learning one key a week. In 3 months you're done and you have total visualization of the fingerboard! Then do the same with the melodic minor, harmonic minor, diminished and whole-tone. I would also spend time learning to play all the scales on one string.
- Spend time with chords and build a vocabulary of ready-to-grab voicings. Start with root on 6th and root on 5th string chords and get to know the shapes. There should be no hesitation in being able to grab, let's say F#7sus4 or Gmaj7#5 in two positions at the drop of a hat. Get a chord dictionary if you have to but realise that it is better to be able to figure out extensions and alterations to a chord yourself. Then move on to root on 4th string chords and after that, the inversions. Phew!
- Develop your ear! Transcribe and memorize. Learn how harmony and chords function.
- Develop and practice a repertoire of tunes in the genre of your choice. Learn to play the rhythms, chords, melodies and solos. You want to be able to function with other musicians and repertoire is your currency.
- Choose a new style or genre of music you find appealing and work on the stylistic elements of that genre.
- If you're so inclined, spend at least several hours a week writing you own material. Make it original and be careful not to be overly derivative.
- Learn to sightread, or at the very least, read. Standard music notation, folks.
- Spend some time playing along with CDs. This will greatly improve your technique, touch and tone and sense of phrasing. You can do this with solos that you have transcribed and memorized or you could do this while improvising along with the recording which will help more in developing your own style.
- Spend a lot of time just listening to music, and tune in to what you're trying to play. If you're trying to play bebop and all you listen to is rock... it will be a long road.