To check if a cue is straight, sight down it like a rifle. Rolling on a table will not prove that it is straight.
Do not expose cue to extremes of temperature. Left in the back of a car or on the radiator at home will certainly make it warp.
Do not expose cue to damp. It might make the cue warp, and it will make the glue used in the cue manufacture swell and come out of the wood joints.
Always keep your cue in a rigid case; a soft case is for transportation only. Nearly all complaints of a cue’s warping, is because the owner’s keep them in soft cases.
When you keep it in a case, do not put anything else in the case, which stops the cue laying flat. For example, some people put glue, tips or cloth inside, this is OK, but if they move, the cue could be resting on them. Not good practice.
If you must keep chalk in the case, try to keep it away from the cue. (It’s best in a plastic bag) Chalk is very abrasive, it will wear the joint each time you assemble the cue, and also the chalk powder gets into the grain of the cue and often colours the cue to a tint of blue or green depending on the chalk used.
Do not let the tip get too low, have it re-tipped regularly, if the tip is low damage can occur to the ferrule and to the ball that is struck.
To clean the cue use a slightly moist cloth, immediately followed by a dry one and buff up with the dry cloth. Do not use furniture polish, linseed oil etc, they usually make the cue tacky.
When chalking your cue, be careful that you don’t catch the wood with the chalk just below the ferrule. If you have a blue or green mark in this position (just below the ferrule) alter how you chalk. I have seen cue’s so thin that the top has broken off.
Do not drop or bang cue down on the floor in frustration. This will loosen the steel or lead weight that was put in during manufacture, and is very hard to repair.