I hate groups of people who undertake certain actions due to their corrupt life philosophies, but I can't say I really hate anyone as an individual.
Hatred is a form of anger. Keeping hatred under control may have to do with anger management skills. It also has to do with strength of feeling for a person, or how much you've been abused by a particular individual. It's not strange to begin to hate a person who keeps verbally abusing you, for example.
Sometimes hate is also anger or depression focused on to individuals that a person feels hurt by, or just on people they don't like.
The best way to manage hate is to keep things in perspective, try to talk to people who care about you or love you, and think through things.
It's easy to keep hate under control if you're empowered, I think. It's very difficult to do so if you feel weak or abused or at a disadvantage for some reason.
I find it's a good idea to vent hatred somewhere, but it's not always a good idea to do so if that hate is focused toward things people can't help i.e. their gender, race, ethnicity, cultural background, sexual preference. I have absolutely ZERO comprehension why people could hate for those reasons, I'm utterly at a loss.
Like I said, I tend to hate hazy groups of distant people with bad morals or corrupt ethics, so essentially I hate their behavior. And generally if I hate an individual it is because they have repeatedly hurt or angered me in some way, in a very pointed and deliberate way.