Building a Line - Part 1
Once you start getting some building blocks into place, you want to be able to use them in a musical manner to build a good sounding line. Having a lot of theory and "chops" is all well and good, but you have to be able to use them in an interesting as well as melodic manner. Too many players get too wrapped up in how many notes they can play, rather than the quality of what they play. You want to balance this with good sound musical ideas. There are several ways to go about this.
First, think of your solo line as telling a story, like a novel. You don’t want to give the ending away at the beginning, but rather, you want to develop the story slowly, building gradually. For instance, use simple ideas inside the arpeggio of the chord with lots of space at the beginning to lead the listener into your "story" slowly. A lot of fast lines at the beginning can be impressive, but too often you will run out of ideas or your solo will lose momentum too quickly. By starting slow and inside the chords, you can then develop momentum to get into those fast, or "outside" ideas.
As you continue to build the ideas, you can gradually increase the complexity. This can be done in several ways. For instance, you can increase speed as you get deeper into your improv. Do this gradually over time, or in spurts here and there for dramatic effect. You can also start working "outside" the changes to build tension and make the listener want to hear that return to the key center strongly. For example play ideas the imply alterations over your dominant seventh chords in order to make them resolve even more strongly to their tonic chords. For any dominant seventh chords that are not functioning as V chords this still works. You can also use the ideas from the last several articles to extend just about any chord to give it more "color".
Good melodic force is another way to keep your lines strong and interesting. A line with good melodic force could be looped back to itself at the beginning, and there would not be any point at which the line would sound like it comes to rest. Listen to just about anything by Bach and you will hear what good melodic force is. This is a difficult thing to do on the fly, but the better you get at it, the more power and drive your ideas will have.
These ideas are a simple starting point, but will go a long way toward helping you build much better lines. As with many other things, quality is always more important than quantity ,and it is more important to keep the listener with you than try and impress people with your technique. Remember that the listener is playing an unconscious game, trying to guess what you will do next. If they are right all of the time, they will stop listening and say you are too predictable. If they are wrong all the time, they will say you are making no sense and quit listening. You are trying to walk that tight rope between giving them enough they can guess right and enough that you surprise them at times. Then you will have built good, strong, interesting, and musical ideas.