I'm playing grand theft auto 5. I needed to earn money from any character of GTA. So how can I earn money easily?
Save all your money from missions, etc, if you haven't had any bonuses. Then when you do the Franklin Assassination missions, Lester will tell you what to buy and sell on the stocks market before the mission. (There are many guides about the assassination missions, for instance this one)
This is the best way to make money in a non-cheating way.
Ofcourse just play the missions and do the heists, they bring in good money too.
As this is single player and doesn't hurt anyone but would only improve your experience (Allow you to buy properties and cars etc.) I'd also recommend getting Cheat Engine and a GTA5 file for it. There are plenty of videos on youtube that will explain how to use it.