Practice. Practice. Practice.
That’s how you become good.
You know where you live. (At least I hope so…)
You live in a state, county, and maybe even in a municipality (city, town, village, borough, etc.)
That means you will have a state police/highway patrol, county sheriff, and possibly a local municipal police force.
Each will have its own dispatch/operations frequency or talkgroup if they use a trunked system.
You should know what State Police/Highway Patrol troop covers your area, and what precinct your local PD your neighborhood is in (if your town/city PD is that big).
That should be three frequencies and/or talkgroups.
Go to Radio Reference.
Select your area.
Program in the necessary data.
Go to the local dollar store and get a composition-type notebook.
If there is too much traffic, then just listen to one. Start with your municipal PD or county sheriff if you live in an unincorporated area.
Listen some more.
Keep taking notes.
Do it for a week.
Then do it some more.
Keep practicing. That’s how you become good.