| You can study music theory all day and be able to recite it for hours on end but its all about being able to add what you learn as far as soloing into a pool of useable tools which you pull out without even thinking when ur soloing.
When I first began soloing, I just relied entirely on default scale choices and really wasn't playing with as much emotion as I would have hoped to. I could get through a chart but I wasn't playing like I wanted to.
I then broadened my soloing horizons and made sure my scale vocabulary was completely up to date with major scale harmonizations, minor scale harmonizations, and melodic minor scale harmonizations, not to mention whole and half diminished scales, bebop scales, and pentatonic scales.
Once you start playing with emotion in your solos music really becomes a part of you. I remember how I used to think so mechanically when I would read a chart but now I just look at it and I can play how I want to over any chords and thats how you know youve developed your own style and can really showcase yourself as a musician.
A HUGE SUGGESTION that I will give to you is to buy the book THE JAZZ THEORY BOOK by Mark Levine and work through it page by page. If you have studied jazz before reading this book, it will solidify what you already know and fill in the gaps of things you though you knew. Mark Levine goes very in depth but in an understandable way that really helps you see the big picture. Though the book is not for bassists or any instrument per say, anyone can take something from reading the book.
I'd also recommend buying the program BAND IN A BOX. It is an excellent program that has chord charts built in and you can actually full on jam with your computer. Just turn the bass off and you can play your own groove along with it. If you can't think of a line, just sight read the line they automatically have made for the bass part! It's truly an excellent program that I recommend for everyone.
Soloing is a big world and theres no real right or wrong way to do it. You can be very abstract and altered like Thelonius Monk or be as in the box and groovy as you'd like to be. There's so many paths to take and so much to know that soloing style is actually what sets apart musicians because when the talent is everywhere, theres only so much that can distinguish musicians.
Hope this helps! | 
