Ingenuity?

[Alistaire]

While leveling you might use it on higher difficulty recipes such as housing items, iirc it should help.
Later you will be using it for anything above level 50 such as 1,2 or 3 star recipes.

You can try to craft things here: http://ffxiv.lokyst.net/

It's a help on all synths now. They changed it from "lowers synth to your level" to "lowers synth level a small amount". It's not a huge help, but if you find yourself with more cp than you can use for touches but not enough for a mend, go for it.