Your main priority is to finish the synth.
Your secondary priority is to get as much quality as possible, both to increase your chance of HQ and to increase your XP.
That being said, you will need to mentally count out how many Touches (i.e. the Quality increase ability) of the kind you want to use you can do. (Some tradeskills have multiple kinds at higher levels.) Whatever CP is left over divided by 12, rounded down, is how many attempts you can reasonably skip. If you want to use Ready Hand, you have to deduct that out of that total, deducting multiple times for multiple uses.
Let's say I'm making Ash Lumber. Ash Lumber has 34 Progress (I think) and 40 Durability, and I'm sitting on 186 CP. My Craftsmanship only lets me progress 30 on each success. That means barring any other abilities mucking with Durability, I have up to 2 chances to use Basic Touch.
Since I have MORE than enough CP to use Basic Touch (24 CP) twice (x 2) and I have some other abilities, I start off with Ready Hand (22 CP). So that's (24 + 24 + 22) CP accounted for, or 70 CP. Since I have 186 CP total, 186-70 = 116. 116/12 = 9.66666666... so I can skip results 9 times without ******** up what I was planning to do. If I don't want to take a risk on the final combine, I'll throw in another Ready Hand right before doing Basic Progress again (assuming bad luck running out the uses of the first one) and 116-22 = 94. 94/12 = 7.833333... So throwing in a second Ready Hand to guarantee my Basic Progress dropped my skips to 7.
You may run into the situation where you've skipped the maximum number of times and it's stayed on Normal the entire time. Oh well, just use the CP you reserved for Basic Touch then and finish up the synth. There's not much you can do in that case.
Edited, Jun 23rd 2013 6:47pm by Ravashack