I am assuming that your songs have a basic verse/chorus/verse sturcture.
A basic solo is a variation of the verse or chorus-depending on where is is located in your song. Basic songs don't really take off on a solo with a totally new direction.
Play the melody, in notes, a few times, then spice it up, throw in a few extra notes-slide between some, play then twice in double time, play every other note an octive apart, play 3 notes then a chord-experiment. After a while, something will click and you can embelish it until you are satisified.