I live in an old trailer with old bad wiring. The fuse box keeps tripping. Would a UPS help me have a more steady power supply?
No. Less power usage would help.
Trust me, don't overdo it on a circuit breaker that keeps tripping. I couldn't figure out why mine was tripping with just a 5.5amp A/C, single 5870 computer miner, and refrigerator on the circuit. Way less than the 15 amps that the circuit was capable of. It tripped three times over the course of 4 days. Turns out, I had a bad plug that the A/C was plugged in to. My wife was home, happened to go into the room that the A/C was in, and saw a flame shooting out of the plug. It very well could have burned down our house if she wasn't in the right place at the right time.
If a circuit breaker is tripping, it is trying to tell you something. Figure out what that something is. You're drawing too much power, and that's due to either having too many devices on the circuit, or bad wiring/plugs causing too much resistance in the line.