You shouldn't have to keep replacing your belts. If the belt isn't glazed, the pulleys could be...you can try burnishing them with a wire wheel or something. Or, I suppose, whatever you're adjusting isn't staying adjusted. But, if your belts are healthy, you can try some belt lube...yes, it's lube, but it's also sticky and can actually help the belt grip better. If nothing else, it'll slip quieter!
You don't usually notice power steering belts slipping until you are doing a hard turn at low or no speed. If you're hearing it on startup, it's most likely your alternator belt. Your alternator might be working hard to charge your battery back up if there's a parasitic draw or if your battery is unhealthy, and the excessive load causes the belt to slip. It can also slip if it's getting wet while parked.
You might find a different way to tighten your PS belt. Or leave it alone, since, as I said, it shouldn't slip except possibly under heavy steering load, which doesn't necessarily happen often.
I'm not sure if Redpoint5's point is to "know when to cut your losses" or if it matches my own, which is that it's sometimes painful to watch antics like these happen over and over, usually to the same people...most of us have been there, but most of us don't advertise it!
Whatever...as long as you're having fun and, hopefully, learning along the way...