A more succinct heirloom guide:
-Never loom an item to +1, always trade your heirloom point for the +1 item+gold, or save up 2 heirloom points to trade for a +3 item
-Never loom anything but gloves. You can trade +3 gloves for pretty much any other +3 item+gold. The lone exception is newly-added items (for instance, the new brigandine armors when they first came out). These are often worth more than gloves for a few months after they are added.
...and that's about it.