Read chapter 1 of The Tone Manual by Dave Hunter - the bit about the actual guitar, not pedals, strings, plecs, amps etc.
Too much info to quote here
He discusses an awful lot about the whole subject - materials, components, fit, electrics, the whole lot.
After reading and digesting this chapter for a while, I tweaked one of my Squier bolt-on bass neck fits and its nut to see what happened.
It brightened the sound considerably, both acoustically and electrified.
I then noticed that these tweaks were already incorporated on my Bill Nash "1965" Strat. which is a very bright machine.
Interesting stuff which stopped me spending loads of money on a la di da bass.