Practice !
Understanding DOF
Aperture
Shutter Speed and ISO ...
Once you understand DOF , and how Aperture , shutter speed and ISO relate to it ( DOF ) , then you are on your way ..
How do you plan to Macro ?
Free hand , tripod , with or without a flash ?
Really close ( 1:1 ) or a little further away .
I would suggest buying a figurine , a small one ..
Set your camera on a tripod , and start taking photo's of it ..
Start at maybe 12 inches and work your way closer ..
My suggestion would be to maintain a decent shutter speed and see what happens with aperture and ISO ..
Then swap to maintaining a decent aperture and see what happens with shutter speed and ISO
And so forth ..
This will hopefully give you some idea at what distance you can take a decent photo ...
Can you guess the distance from the front of the lens to the subject in this photo ?