go to the rock star social club website (see Google) then when your there check the custom published creator maps that others have put together. do a search for (RP) it should come up with a few different ones. some of these are very simple and quick to do so keep in mind its about gaining RP and not always about killing everything in sight. they also need 2 people or more, so you need a friend to help you, and most are only on a minute or 2 and boring. but repetition is the key. we just ranked my son up in a couple of days to 50. You tube also has some vids and links to RP created online maps.

good luck

freight train WTF you tube channel has an easy one at the air force base but not as quick as some of the others I've tried.