Right....I'm not an expert, but here are the basics.
To improve HQ chance you can:
- Stand facing the right direction (based crystal - direction for HQ is same as skillup).
- Be high skill level. This is the most useful.
:1-10 higher than cap = approx HQ chance of 1-2%
:11-30 higher than cap = approx HQ chance of 5-10%
:31-50 higher than cap = approx HQ chance of 25-30%
:51+ higher than cap = approx HQ chance of 50%
- Do it on a full moon, or close to one. This is really helpful I find. I have no real knowledge of new moon crafting.
- Do it on the right day (weather may well affect this too - I don't know).
Here are a few sites that may be useful to you:
http://ffxi.lokyst.net/timer/crafttimer.html
There was another one that was really cool, but I can't find it right now >_<. It told you %age modifications to HQ chance and fail chance based on Crystal type vs Day.