Keeping a LP in tune

Just picked up a LP Calssic. It just wont hold it's tuning. Any suggestions

There are several things that may help providing the guitar is not broken i.e slipping machine heads, cracked body etc

1) Tinning new strings. This is where you place a small dollop of solder around the string wind that keeps the ball end of the string on. This prevents some stretching

2) Putting a small amount of lube (I use chapstick) on both the nut and the bridge surfaces that come into contact with the string (not too much now !) this can work well with trem systems so may not be so good for an LP

3) Winding on more string at the peghead. B. B. King is quoted as saying this is a very cool way of sating in tune even though I think it looks ugly

4) Monitoring humidity. Atmospheric humidity can cause wood to expand and there's not much you can do about this other than crank the AC. I moved from London to Iowa and the difference in winter time and summer time humidity here amazes me. I don’t know what to do about this other than to use a guitar case humidifier in the winter and keep retuning in the summer

Dr_simon's points 3 and 4 are especially pertinent.

Also check for the basics,make sure the stop bar is snug against the posts and the strings are sitting properly in it..and that they rest in the bridge saddle notches ok.
Gibson nuts seem to be cut for light 10 gauge sets,you can get problems in tuning if the strings are too large and binding,etc.

Aaah... windin gtoo much string around the peghead can alsoo cause tuning problems, as it allows the string to develop a lot of slack. Two winds around is generally enough to stop the string slipping, and in my experience is more reliable than winding it around heaps of times. Remember to stretch your strings in a bit before playing. Gently tug the strings (GENTLY) away from the fretboard, moving up the neck and back, then tune to pitch. Do this a couple of times and your strings will stay in tune much better. ALso, the chapstick thing is a good idea; lots of tuning problems come from the strings binding on the nut.

Good point,Bardsley...1 to 4 winds is way enough(call it senility ,me forgetting to say that), less on the thicker strings,just so the winds don't slip over each other.

[Small tip : hold string down so it locks under the first wind,and keep going under.]

You can check the nut slots by pressing on one of the strings between the nut and the tuning machine post. It should go back to pitch after you release it. Some players use this feature to do a one-string 'whammy', so don't be shy about it. If the string stays even a little bit sharp, its binding in the slot.

check or get your nut checked for problems.....heres a little test to do that can determin if the nut is seriously bad......tune your guitar and then double stop tune it(i.e 17 fret b and 12 fret high e)if its out of tune up there somthings wrong.....i had that problem with an ibanez gio but i assume there not much of a difference if at all.............good luck!