Determining who might be a member of a gang needs to be done with caution and without assumptions. Racial profiling is especially dangerous. Curiosity is not a reason to try and find out. If you need to know a person's gang member status, be respectful and remember that gangs are really families to some young people.
Ask. It is the easiest way to find out anything. If you ask someone with respect and a genuine desire to know, he or she is likely to give a truthful answer.
Be curious about the gang and what it means to the person. If he admits he is part of a gang, find out what the gang means to him and what it represents to his community. Yes, many gangs have "gangbangers" out shooting up everything and each other. But some gang members are just kids with no home life trying to make a way of life with stability and culture.
Are tattoos and clothes really a sign? Yes and no. Jail tattoos (done with pens usually in one color and looking amateurish) can say a lot about a person's criminal history. But does it mean the person is in a gang? It might. Again, ask. A lot is made of "colors" flying blue or red clothing, and things like bandannas establishing gang affiliation. But it might also mean the person had clean blue clothes that day.
Be safe and smart. Don't follow people to see if they hook up with a gang and then go out shooting guns and threatening people. True criminal gangs can be every race and male or female. Other than the police or other law enforcement, no one needs to clarify for certain if someone is a gang member. If someone is dating your kid, and you want to know, ask. But don't profile or assume one race wearing one color means anything. That puts you in a gang of people who judge.
If you don't know gang lingo, don't throw out what you think is gang talk and expect someone to relate to you.
Don't ask to buy guns or drugs to determine if someone is in a gang. You're breaking the law by asking.