Petitions are effective in that they raise awareness. However, government officials are not required to take action based on petitions. Keep raising awareness but also: Take time to educate yourself and your friends. Read books. Support black businesses. Call your representatives and advocate for change. Protest (if you feel safe and are able to).
With that being said, here are some petitions that still need to reach their goals. Feel free to sign them. Make sure to use your real name as petitions do lose credibility if there are false signatures on them. If you're looking to start a petition, petitions.whitehouse.gov is the most effective site as signatures go straight to the white house.