This article may help you, courtesy of http://www.haywirecustomguitars.com/58.html

-How does the tone capacitor value affect the sound of the guitar?
Most guitars and basses with passive pickups use between .01 and .1 MFD (Microfarad) tone capacitors with .02 (or .022) and .05 (or .047) being
the most common choices. The capacitor and tone pot are wired together to provide a variable low pass filter. This means when the filter is engaged
(tone pot is turned) only the low frequencies pass to the output jack and the high frequencies are grounded out (cut) In this application, the capacitor
value determines the "cutoff frequency" of the filter and the position of the tone pot determines how much the highs (everything above the cutoff
frequency) will be reduced.

The rule is: Larger capacitors will have lower cutoff frequency and sound darker in the bass setting because a wider range of frequencies is being
reduced. Smaller capacitors will have a higher cutoff frequency and sound brighter in the bass setting because only the ultra high frequencies are cut. For this reason, dark sounding guitars like Les Pauls with humbuckers typically use .02MFD (or .022MFD) capacitors to cut off less of the highs and
guitars like Strats and Teles with single coils typically use .05 MFD capacitors to allow more treble to be rolled off. The capacitor value however, only affects the sound when the tone control is being used (pot in the bass setting) The tone capacitor value will have little to no effect on the sound when
the tone pot is in the treble setting.



-What is the difference between 250K & 500K pots?
Either 250K or 500K pots can be used with any passive pickups however the pot values will affect tone slightly. The rule is: Using higher value pots
(500K) will give the guitar a brighter sound and lower value pots (250K) will give the guitar a slightly warmer sound. This is because higher value pots put less of a load on the pickups which prevents treble frequencies from "bleeding" to ground through the pot and being lost. For this reason, guitars with humbuckers like Les Pauls use 500K pots to retain more highs for a slightly brighter tone and guitars with single coils like Stratocasters and Telecasters use 250K pots to add some warmth by slightly reducing the highs. You can also fine tune the sound by changing the pot values regardless of what pot value the guitar originally had.


As for the type of pot, most websites recommend audio taper (ie logarithmic) pots for both volume and tone controls.
However, i personallly like using linear pots for volume and log for tone (as do Ibanez on most of their guitars). Makes the volume pot more balanced throughout the range of travel.

However, if you like to 'violin' (ie volume swells) using the volume pots, then log pots are better since changing with small movements from 8 to 10 you can get a bigger change in volume!

cheers
geoff