A ukulele forces you to make chords out of, at the most, four notes. This simplifies the chord shapes in your mind. You start to see the patterns of, for instance, the relation of the other notes near the note you are playing on the C string (on guitar this would be the G string) and then, when you are back on guitar, the pattern is there. I'm telling you, for me, starting to play ukulele provided a real boost in my soloing and my chords.
Another thing that will help your soloing is to be mindful of your hand positions. If you are making an extreme movement to get to a note, well, you're getting out of position and you are going to hit a wrong note. Everybody learns how to play a scale vertically - without moving your hand up the neck. Start practicing scales in the pattern of two strings, slide up a fret, all the way up the scale, maintaining your hand position. If you start your major scale from the first note, then the second, and so forth, you will be covering all of the modes.
Finally, if you can get your paws on a copy of The Alchemical Guitarist vol 1 DVD, which consists of lessons by Richard Lloyd, which originally came with Guitar World magazine as a column, you will find a wealth of information that will be helpful to you in ways that no other guitar instruction I've come across has possessed. I didn't see it for sale on Guitar World's site, though vol 2 is there (I just ordered it this morning), nor on Richard's site. Perhaps if enough people requested it it would be put on sale again.
I cannot stress enough how much Richard's lessons have helped my playing. There is an example lesson on youtube, how long it will be up there I don't know. When I first watched this lesson I had to rewatch it about 20 times to understand what he was saying, and then it was like a light bulb went off in my head. Here it is: sample lesson from Richard