I seem to be unusually hard on my rear wheels -- they need to be re-tensioned and trued about every six to eight weeks -- and I'm looking for advice or routine maintainence to keep from having to bring them to the shop to have them trued all the time.

I commute about twenty miles round-trip, five days a week, mostly over smooth pavement (maybe a mile total of slightly rough road or gravel path). I'm a reasonable weight (about 165lb), and I carry a fairly light load (five to six pounds, on an aluminum rear rack). The wheels I run are cheap, but should be reasonable for this kind of use: 32h Alex rims, stainless spokes, cross-three. I've had this problem on two different wheels from two different vendors, so I don't think it's just a single weak wheel.

So, is there anything I can do to keep the tension better and the wheel truer as part of my regular maintainence schedule? I do pretty much all my own maintainence except for wheels; I'd like to learn how to maintain my own wheels too, but I can't afford a truing stand or a tension meter right now, and I've had poor results with trying to true it in the frame and feeling the tension by squeezing the spokes.

Any help or advice is appreciated.

Wheels shouldn't be going out of true while JRA, so something is wrong. The usual culprit is insufficent spoke tension, and plenty of bike shops seems to be blissfully unaware of how to set that up. Can also be that you're getting spoke wind-up, which also would explaing why your wheels are getting out of true repeatedly.

With that said I guess it's not entirely impossible that you for some reason have gotten a batch of spokes/nipples that simply are more prone to unwind than other.

If you really are significantly harder-than-average on your wheels you might benefit from a rebuild with butted spokes. DT comp on the DS and DT rev on the NDS (or the equivalent spoke gauges from another manufacturer) will usually result in a nice tension balance. Some mild threadlock with linseed oil being a personal favourite can also be helpful.

Given your weight and the type of riding you do, even those cheap rims should stand up without needing to be trued all the time.

My guess is low tension in the first place; IMO you should start learning how to use a spoke wrench, since you can do everything else... there are plenty of how-tos on the web - check out Sheldon Brown's site or a start.

Try adding a half-turn of tension to each spoke (flip the wheel to check you haven't put the dish out), or maybe a full turn if they're really loose.

Get a feel for good tension by giving the spokes a squeeze on good wheels (around the same spoke count).

Once you have enough tension, your spokes shouldn't unwind due to the friction.