Just hold shift and press alt, the just press alt key and you will be hidden without pressing shift. You can do this for any key.
Using shift the whole time seems like a waste. I personally wait at spawn until all those diamond armor pkers leave, then book it with a speed potion for about 500-800 blocks away from spawn. Then I start mining safe with the knowledge that most likely no one is around me. I only bring in iron armor! Set home once you're out there and hit /spawn to put your stuff away, then when you return use /home and your far from spawn again where the campers are. I never knew about the three-button safety "command" though. That's a nice trick! I'll be sure to use it from now on.
Another tip is to speak in Local Chat every once in a while. If no one hears you, that means there arent any people within 250 blocks. Please correct me if Im wrong about the block distance.
Yea, using shift seems like a waste... Some one in mining world mined right by me, coming within 5 blocks of me. I thought he was a pker, but then he went right by me. Oh yea, I was holding shift x.x. . I later talked to him and he said he never even knew i was there. I could have even killed him if I wanted to, but im not like that. Not everyone is as nice as me. If you are not careful, just know the risk your taking...
I mean the thanks also look at mining world descussion and the top 10 or so posts are replied to by me