Other than a metronome you could simply play along to CD's or get a drum program like BFD, which is really cool, or a a loop based program like Acid Pro. I think practicing to actual drums is easier than a metronome.
If you're used to playing sitting down, but get all screwed up while standing it's because you're use to having the guitar at a specific level. Try playing standing with the strap adjusted at a higher level and gradually lower it until you get used to it... Or you could simply adjust the strap to your desired level and just get used it. May take a few days for your muscles and joints to adjust to it.
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I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it.
- Thomas Jefferson
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I don't need anger management... You just need to stop pissing me off!!
If you make something idiot-proof, someone will just build a better idiot