When you say you're 'trying to let it dry out a bit' between waterings, what does that mean - does it mean 90% of the soil is still on the soggy side from previously, or 50% of it's dry down into the pot? If it remains soggy, you need to repot yesterday into a gritty, fast draining mix and don't ever allow the pot to sit in drain water. Once that's done, with no peat-based potting soil in the mix, you will be able to water more often with less risk of rotting (peat never dries once it's wet). You might also post on www.bonsaitalk.com as I think there may be more people there with more knowledge of your tree.

I mean that I let it dry most of the way out; it's already in a gritty mix that drains fast, and I always make sure that it doesn't sit in drain water. Thank you for the information, though!

More light? When you say 'plant light' - do you mean a really strong fluorescent, or some blue thingy from the supermkt? Lots of humidity? Mites?

All I have available to me right now is a little 60 watt plant bulb I picked up at Lowe's (blue thingy, in short.) Is there a stronger option that I could use other than buying a large fluorescent setup? Something like that might work while I'm at home, but most of the year I'm crammed into a dorm room.
I wasn't sure about the humidity since acacia seem to be from a more arid climate, but maybe that's a factor as well; today it's been close to a humidity source (not a humidity tray, but if it needs one I can easily set one up,) but I'm not sure if it's helping or not. I haven't noticed any signs of any pests on it, either, thankfully! Thank you again for your help, Lucy. =)

Go to any store (food, hardware) that sells light bulbs and get one of the new fluorescents. It'll cost a couple of dollars more, but it'll be better for the tree. When you can afford it (though whether a dorm is suitable or not is another story- electricity costs money) get a 4' long fixture with 1-2 T5 full spectrum fluorescents, which will be effective for 6 months, after which you'll need to replace the bulbs as their half life drops right off even if you can't tell the diff. by looking - in other words they're good right through one winter season (Oct-Mar). BTW, even in supposedly very arid climates there is still better humidity than indoors here, so a wide tray of pebbles and water under the pot is a good idea (better than spraying) as long as the pebbles keep the pot above water). But light is really the thing and it should be above the tree by 6 inches for 16 hours a day.

You might know this already,but if you dont,there is a great site from the South African Bonsai society with the worlds best Acacia Bonsai for inspiration.

Azaleas generally need to remain slightly moist throughout - the one plant that you shouldn't let 'dry out' between waterings. And in Arizona, unless you keep it well watered, you really may have a problem.

Acacia or Azalea?????-lol Um,two totally different plants!