In final fantasy 12 how do you use quickenings to the full advantage?

Answer 1

To use them to their full advantage you want to chain the quickenings together to get a stronger concurrence. Here is a chart, from weakest to strongest:
--------------------------------------...
Concurrence - Quickening Level - Amount -
--------------------------------------...
Inferno ------------- Level 1 ------------ 3 Times
Cataclysm -------- Level 1 ------------ 8 Times
Torrent ------------- Level 2 ------------ 3 Times
Wind Burst -------- Level 2 ------------ 6 Times
Whiteout ----------- Level 3 ------------ 5 Times
*Ark Blast ---------- Level 1/2/3 ------ 2 Times Each
*Luminescence -- Level 1/2/3 ------- 3 Times Each
*Black Hole ------- Level 1/2/3 ------- 4 Times Each
--------------------------------------...

*Means you have to perform a level 1, level 2 and a
level 3 in the amounts stated

I got the chart from this site:
http://www.gamefaqs.com/console/ps2/file/459841/46039
I recommend reading this whole page on GameFAQs, it explains the quickenings in a bit more detail!