Tune by harmonics to hear, and feel, the beating effect better.

Lubricate all string contact points with pencil lead, to prevent snags.

Store your guitar in a room with a constant temperature. If the temperature varies widely, it will go out of tune, which is a symptom of wood expansion & shrink -- a guitar killer if given time to work.

Yeah, I would stop selling that one, as it's a load of crap. Putting pencil lead on the pegs prevents sliding, not snags. It doesn't make the string slip easier. It prevents it from slipping. Most of the time. It's a trick of the trade that 90% of string players know. Ask any string person who's been playing for a bit. The pencil lead helps hold the tune by keeping the string from slipping. Not aiding it to slip.

Using the pencil lead is a good idea, to keep the string from slipping. Such a good time to use this trick: When the string is slipping and loosing it's tuning.

That's funny .. I've heard of the pencil graphite trick, but the way I heard, it was also supposed to help lubricate the string so that it would slide through the groove on the bottom nut (or whatever you english speakers call it) better.

Sometimes it will, Tore. But we're talking about once the string is already in the ring nut. It does make it smooth going through the ring nut on the bottom, but it keeps the strings from slipping on the peg. Which if you're having issues with your tuning slipping, the pencil lead on the peg helps.