Depends on what you want to do.
Streaming is probably the easiest thing to get into because you can turn it on and just go. X-split is the biggest streaming program that I know of, but you can google for others. You need just a streaming program, an audio mixing program (google for them) and a decent headset and mic.
Recording videos for something like Youtube is a bit more of a hassle. You need all the programs I mentioned above, plus Video editing software like Adobe premiere, capturing programs like Fraps plus at least one other back up program. Then you need an idea. What do you want to do with your channel, what kind of videos are you going to make.
The same goes for streaming, but I feel like streaming is a bit more lax. Although your limited to the games you can play on Twitch. Not that you can't play anything you want, but if you ever want to get a following you are certainly going to have to start by playing games that have some sort of twitch audience. You want people to stumble across you playing a game that they know, bring people in with some sort of familiarity and build a following through that. Then you can expand.