Depends on context of song. Or better yet, depends on your interruption of what emotion you are trying to convey. If you are in a setting with other instruments you might need to stand out during your solo. That could be boosting your volume. Adding Overdrive. Or using a modulation type effect.
Also either boosting the treble or mids could help cut thru during your solo.
A good rule for standing out is to make sure that you are within your instrument's tonal spectrum. Example is a bass guitar handles the low range and the guitar handles the mid range in a song. If you stay in your range/spectrum you are already standing out and just a little change in your tone (whatever effect you use) during a solo will have a great affect.