Hi, i'd like to gather information.
but I have a problem.
1.I do not know what information to gather
2. I do not understand how izaya gather information about humans
3. The only way I know how to gather information is the resources around the web and observing (is that all? give some ideas please!!)
Thank you!!

Takes a lot of skill first off.

You need to be extremely social. Make connections with people across the community and online. You have to bend your personality to match the person you speak with. Some people find this unethical but this is the way to go.

Gain social skills and observe human behaviour to it's finest details. This'll help make proper connections.

It's not very logical to do the underground business which Izaya does in the anime. Instead you can help others such as gathering appropriate information from one of your connections to another. Let's say there's a new business that's opened up, you know the boss and they're looking for a certain type of employee. You know someone else who's looking for a job and fits that category. You put them together and boom, everyone's happy with your service. This is just one of the examples.

I'm not so bothered going through the steps. If you're dedicated enough to follow this line you will find these steps on your own, but good luck.

Hmm.. thanks Hudey-chan! i'm really interested in humans but I get confused of myself because I cannot find the thing I'm interested in, though something still attracts my attention.. haha, better find out now!! bye bye~