Composition isn't something that gets discussed much in the scratch community. However, without it music lacks structure and without structure music is essentially just a bunch of noise. This holds true when any instrumentalist solos as well. A well composed solo is a great solo. Likewise, if there is little to no thoughtful composition in a scratch solo it will not be enjoyable to listen to.
Composition tends to be thought of as a written process, yet in scratching writing out your solos is very rare. However, just because the bulk of scratch solos that exist are improvised does not mean that they can't be well composed. If that were the case, all the greats of scratching would sound thoughtless and unconvincing, thus there'd be no great scratch dj's.
Know Your Audience
Whether your audience is comprised of other turntablists or people that have little to no connection with turntablism, one thing bonds them together. If your solos lack structure, they will notice and subsequently be turned off. They may not be able to put what they dislike into words, but they will naturally lack enjoyment from what you're doing.
Improvisation Love it or Love it
Let's face it, if you don't enjoy improvising you better learn to or switch instruments because the backbone of scratching is and will likely always be improvisation. So how do you give your solos a feeling of quality composition if everything you're doing is on the spot? Well there are many ways, but one simple yet effective way that you can implement immediately is repetition.
Repetition Gives a Feeling of Structure
If all of your solos are just one long string of different scratches where repetition comes few and far between the audience never has a chance to feel anchored to what you're doing. It will fly right over their heads. If something sounds good it should be repeated multiple times. Get the most juice you can out of it until it's dry. That's why pop songs are so popular because they always have a hook. Don't get me wrong, I'm not telling you to be as maniacally repetitive as a pop song, but you need to get more mileage out of the scratch patterns you know so the audience has a chance to soak them in and really enjoy them.
This is also important when considering that most scratch beats are in a simple, repetitive 4/4 format with no hooks whatsoever. This makes the responsibility of providing a hook like feeling fall to you as the soloist. If you don't do this, audiences that are used to receiving the feeling hooks give off in other genres will be lost and naturally disinterested.
Timing Goes Hand in Hand with Repetition
Don't make the mistake of assuming that simply repeating a combo multiple times at any moment is enough. Timing is still a crucial part of utilizing repetition. Going back to hooks, listen to any major pop tune and you'll notice the hooks are always well timed. This isn't an accident. The goal is to maximize the effectiveness of the hook, so it will often times come after a song has built up a lot of tension and is giving a feeling of beginning to climax.
What this means for you as a scratch soloist is you'll have to feel things out. If you're scratching over a simple 4/4 beat you will be completely steering the ship. If the beat is a little more complex and actually has hooks of its own, you can use those hooks as cues for your own repetition. Either way you'll have to develop a good sense of timing and that comes mostly from experience.
Never Go Too Long Without Repeating Yourself
A good way to get your feet wet with this concept is to simply not allow yourself to go more than 30 seconds at a time without launching into a string of combo repetition. As you continue to do this, you'll soon get a feel for what sounds and feels right as far as when to launch into repetition, how many times to repeat a combo as well as how often. Nothing is a better teacher than experience, so don't wait to transform your scratch solos into breathtaking feats and get started today!