Looking to the community to get some hard advice as to how to go about getting an ”in” with a VC group.

I.e. the VC group or individual buys into a business and brings a pool of resources to ramp up scale and efficiency into the business. Usually this would be from their network, I’d hazard a guess. So is there a particularly good source to offer some pro-bono work to that has a reasonable expectation of pay off if the work is quality?