G'day, I have been taught to do slaps in a few different positions. From the Middle of the drum, all the way to the edge. They all sound different. Which is good, more arsenal.
A good way to practice the slap technique one handed is to place a $10 or $20 bill on the drum. lay it flat and as you slap the portion where your fingertips hit the drum pull the note in. That is, as your hand goes down for the slap, the fingertips pulls he note into the cup of your hand only 1-2cm, if that.
Practice it. IT is hard to write, but easy to do.
let me know what you think. also if you can slap on a loose tumba you can slap on anything.
You could always ask your partner to slap you on the face, the sensation you will feel will give you a better insight into slapping and being slapped. Not that I advocate Domestic Violence. I am not trying to be funny, Albert Einstein said to solve a problem we have to raise above the mind set that created it. so try somehing different. What does it feel like for the skin of the conga to be slaped?
Bless ya
Pidoca
http://www.jessesvoice.org