Using a strip of innertube to line the tyre might help to prevent punctures, but you need to ask youself why
you keep getting punctures?
Is it a particular trail you ride on where you keep getting punctures? is it rocky? do sharp bits of flint stick into the tyre and cause the punctures? or are your tyres under-inflated and so the innertube gets squished against the rim causing "snakebite" punctures? Maybe it's a path next to a hedgerow that's recently been cut and there's bits of thorny hedge laying about just waiting to cause a puncture? perhaps you have a rougue spoke which is sticking through the rim-tape on the inside and causing your puctures? do you have rim-tape on your wheels? maybe your tyres are geting worn out and are more prone to being punctured? do you check the inside of the tyre for any foreign objects after repairing a puncture to ensure any thorns etc are removed and can't cause you another puncture?
there's many reasons for punctures
maybe you should invest in some tyres which have punture a resistant belt built into their design?
Cranks, are they the square-taper type? do they fit onto a square shape axle with one bolt? usually they fall off because they've not been tightened on properly, but if the square hole in the crank arm is a bit worn or rounded-off then it makes them more likely to come loose and round off a bit more before they fall off again. The soft alloy of the crank arms is easily damaged by the harder steel of the bottom bracket axle if they are allowed to work themselves loose.
what sort of riding do you do anyway?