Wash less than you think. Wool is naturally antibacterial and self-freshening — an airing overnight does more than a wash, and every wash is wear. Rotate knits so each one rests a day or two between outings, and you'll wash them a handful of times a season at most.
When you do wash, keep it cool and calm. Use the wool cycle at 30°C with a wool-specific detergent, or hand wash in cool water. Never wring or scrub, and never let hot and cold shock the fibres — that's what felts and shrinks them. Cashmere in particular wants hand washing and a gentle press, not a spin.
Dry flat, always. Lift the piece out supporting its whole weight, roll it in a towel to squeeze water out, then reshape it on a fresh towel away from radiators and sun. Hanging wet knitwear stretches the shoulders and drops the hem out of shape for good.
Manage pilling as maintenance, not damage. Bobbles are just friction where the garment rubs — under the arms, at the cuffs. Take them off with a comb or a fabric shaver every so often and the knit looks new again. Store folded, never hung, with cedar or lavender nearby, and check the folds for moth signs before you put anything away for summer.