There is no magic bullet, there is no one thing that can lead to a revolution, imperial core or not - it is a multi-pronged approach. The pillars that have to be engaged simultaneously upon which any and every revolution has to rest are:

1. Propaganda - word of mouth, social media campaigns, demos, getting into the news with a positive message/spin, viral street art.
2. Activism - taking part in social justice protests, helping materially marginalized and vulnerable populations as well as just helping out in the community, training camps, mutual help orgs, political campaigns.
3. Establishing communes, co-ops, sanctuary cities and regions where socialist policy is implemented.
4. Infiltration and sabotage - getting sleeper agents into positions of power, getting agent provocateurs into hostile structures in order to stage false flag ops and take out those orgs from the inside, whistle blowing.
5. Militancy - bank heists, hostage taking for ransom or in order to enforce/prevent certain policy, targeted clandestine mass assassinations (of cops, military personnel, politicians, bourgeoisie), taking over criminal syndicates.

All of the above done in concert build an actual revolutionary front that is able to wrestle power away from the bourgeoisie, as was the case time and again: Russia, Cuba, Greece, Yugoslavia, China, etc. The only other option that had success historically was a military coup by progressive officers. The second is arguably very unlikely if not outright impossible in the imperial core.