Well 0.6 wire will spool faster than 0.8 to fill the weld pool appropriately. With 0.8 being thicker it doesn't need as much to fill the same gap
The tip should say what wire you have 
Every variable makes a difference. It's a catch 22 scenario really. You need to know how to weld to set up the machine but you need the machine setup to weld.
Too little gas is porous welds, too much interrupts the arc and spatters
Too little wire feed doesn't get the appropriate amount of filler metal in quick enough
Too much causes it to sputter as it stubs in the weld pool and builds up
Then you have torch angle, stick out, burn back, wire stick out, travel speed blah blah blah. You could go on for a while
But you're doing the right thing, practicing
Get an offcut weld a 2 inch bead, make alterations and weld again, see how it affects the weld. Dont go too mad om thinner stuff as the hotter it gets the more likely it is to blow a hole
