[pickleboy]

i would recommend the following progression if using the "p" grit paper.
p320 to start then p400, p600, p1000 wet, p1500 wet. then to the wheels, spiral with tripoli then spiral sewn with white. finally a finish buff with loose and white or red. if using the us grit # i would start with 240 then 320, 400, 400 wet and 600 wet. when wet sanding i add a small amount of liquid dish soap to the water and keep the paper flushed with lots of water. this works good if you have a deep basin or sink to sand in and have the water contained. that way you can sand and dunk the part to clean and rewet.
as for the last part of your question, i dont use sisal on aluminum parts, i feel it scratches more than it helps. i use vented wheels and emory for first cut then if i do it right i can get almost mirror shine from that. then i move to a spiral and white combo. finally i use loose cotton and red for a final color buff. hope this clears things up a little more.