Garments fail in the same places for the same reasons, and once you know the mechanisms most of them are avoidable.
Underarm and collar
Two areas that fail from chemistry rather than abrasion.
Perspiration is acidic and, combined with aluminium salts in antiperspirants, degrades fibres and sets stains that become permanent with heat.
The critical point is that heat sets protein and oil stains. Washing hot, or tumble drying before a stain is fully removed, converts a removable mark into a permanent one.
Which means washing these areas cool, promptly, and checking before drying does more than any product.
Collar marks are sebum, which responds to enzymatic detergent and a period of soaking rather than to scrubbing.
Elbows and knees
Abrasion combined with repeated flexing, which is straightforward.
Thin fabric fails first, which is why lightweight knitwear goes at the elbow and heavy knitwear rarely does.
Leaning on desks accelerates it considerably, which is why the elbow of the arm you rest on goes first and asymmetrically.
Inner thigh on trousers
Fabric rubbing against itself, which produces friction on both surfaces simultaneously.
It affects some people and not others based on gait and build, and it is not preventable through care.
Repairing it early, when the fabric is thin rather than holed, is far more effective than waiting, and a patch applied from the inside is essentially invisible.
Pilling
Short or broken fibres working loose and tangling into balls on the surface.
Shorter staple fibres pill more, which is why cheaper cotton and lower-grade cashmere pill readily.
Friction causes it, so it concentrates where fabric rubs — sides, underarms, wherever a bag strap sits.
A fabric comb or a battery shaver removes pills without damage. Pulling them off takes fibre with it and accelerates the problem.
Washing knitwear inside out in a mesh bag reduces surface friction significantly.
Elastic degradation
Elastane and rubber degrade with heat, chlorine and time, faster than the fibres around them.
Which is why waistbands go slack and stretch garments lose shape while the fabric looks fine.
Tumble drying is the single largest accelerant. Heat is what kills elastic.
Nothing restores it once gone, which makes this purely a prevention problem.
Zips and fastenings
Zips generally fail because the slider wears and stops closing the teeth properly, not because the teeth break.
A worn slider can be replaced by any alterations shop for very little, and doing so before the teeth are damaged saves the garment.
Buttons come off because the thread wears, which is predictable and worth pre-empting — reinforcing buttons on a new coat takes ten minutes.
Moths
They eat protein fibres — wool, cashmere, silk — and specifically the larvae do the damage.
They are attracted to soiled fabric, particularly anything with perspiration or food traces.
Which means storing knitwear clean is the main defence, well ahead of any repellent.
Freezing an affected item for several days kills all life stages, and it is the cheapest treatment available.
What washing actually does
Mechanical agitation causes fibre damage, and more washing means more damage.
Which means the common advice to wash less is not just about water use. Wool and outerwear in particular need washing far less than people assume, because the fibres release odour on airing.
Spot cleaning and airing between wears extends garment life considerably, and it takes less effort than washing.
The drying question
Tumble drying is responsible for a large share of textile damage. The lint filter contents are the fabric of your clothes.
Heat degrades elastic, shrinks natural fibres and sets stains.
Line drying avoids all of it and takes longer, which is the entire trade-off.
Repair
Most alterations shops will do small repairs cheaply and quickly, and most people never ask.
A reinforced seam, a replaced zip slider, a darned elbow or a patched pocket bag are all inexpensive relative to replacement.
The main obstacle is that repair happens after the garment already looks worn, by which point people have mentally written it off, and catching things earlier is most of the skill.
Storage
Where damage happens without any wearing at all.
Knitwear hung on hangers stretches at the shoulders under its own weight, permanently. Folding is the only correct storage for anything knitted.
Wire hangers distort shoulders on tailoring. A broad shaped hanger supports the shoulder line as it was constructed.
Plastic garment bags trap moisture, which encourages mildew and prevents fabric from breathing. Cotton covers do the protective job without the problem.
Direct sunlight fades dyes and weakens fibres, and a wardrobe near a window loses colour on whatever hangs at the end.
Dry cleaning
Worth understanding since it is applied more often than necessary.
The solvents used remove oils, which is what makes it effective on tailoring, and they also strip natural oils from leather and some fibres over repeated cycles.
Which means a suit cleaned after every few wears will age faster than one brushed, aired and cleaned twice a year.
The pressing that accompanies cleaning does its own damage over time, flattening the shape that canvas and careful construction created.