right a soloin F, thats pretty much all I think anyone can say. Or if your looking to improv it just use some scale shapes that are either in the key of F or have the same notes as the chords your playing over.
Soloing isn't quite as mysterious as people seem to think it is, just right a solo part in F for the music you are playing over. It helps sometimes to start with a scale and then branch out, don;t feel trapped in the scale just play what sounds good.
If it is F major use F ionian or another F major scale that sounds good. emphasis the lead tones in the chords your playing over but you don't need to stick with the chords for every single note, play what sounds good to you. It helps **** loads to have the music you are going to be playing it over when writing it.
I usually just improv solos, I have always just sat down and either noodled or done exercises so improv and solos just come naturally to me, but I guess if all you have ever learned is other peoples music then it might seem like a daunting task to improv or write a solo. All you have to do is sit down and play through man and let the ideas flow out. you have to listen to the music and play with it.
Other people would be able to tell ou more specific stuff probably. Check out the theory forum here and look at alot of the stuff dvenetian and others have put up there latey and you should be good to go.