If you're determined that you don't want to do anything illegal, your options are fairly limited (as far as I can tell, only community service is both legal and juice-giving, but it has a maximum of 0 juice). If you mean you don't want to do anything which will generate heat, you have a much better chance. Graffiti can boost your juice up to 50 (can be done very quickly as well); successful jury rigging will get you 25 points of juice, uncapped (i.e. up to elite liberal), but can be difficult with low stats. Destroying equipment at labs (i.e. releasing animals) or sweatshops, is, I'm pretty sure, heat-free, and gives the entire party juice. Similarly for stealing (anything) off the ground.
I really recommend you don't go the "nothing illegal" route, as you'll be severely limited in the number of people you recruit: 6 for your founder and 0 for everybody else. There is no legal activity which will give you the requisite 10 juice to recruit a single member, though some graffiti - and possibly some other minor activities - only criminalises you if you get caught (even then, only if you do it as an activity rather than in site-mode). And, even if you diligently refrain from ever doing anything illegal, if one of your criminals with low heart gets caught, there's a good chance they'll break in prison and get you hit with a racketeering charge (not sure off the top of my head whether it's the liberal's handler or the founder that gets it), which is a 'scary' charge with a decent chance of getting you imprisoned on its own - racketeering is equal to hacking (and publishing secret files?), escaping/assisting an escape from prison, selling drugs and arson. It's only less scary than terrorism and treason - too many counts of racketeering and your efforts of staying clean are wasted.
I'm all for keeping the founder free of the 'scary' charges, but I prefer to have them with maximum juice and skills anyway. When my founder gets caught, I can break him out of the courthouse lockup with a quadruplegic child labourer (which, obviously, dies in the process). My founder makes Macgyver look like he was dropped on the head as a child. That is greatly preferable to having to wonder whether he'll get the death penalty for loitering.