A VHS tape is a length of magnetic ribbon inside a plastic shell, and it will outlive us all if you treat it kindly. Neglect it and it warps, sheds, or grows something. Here is how to keep a collection healthy for decades.
Stand your tapes vertically on a shelf, spine out, the same way you would shelve books. Storing them flat and stacked puts pressure on the tape pack and the reels over time and encourages warping. Upright keeps everything evenly tensioned and, as a bonus, lets you actually read the spines.
Never, ever play a mouldy tape. If you spot fuzzy white or grey growth on the tape edge when you look into the cassette, stop right there. Playing it drags the mould straight onto your VCR's heads, and then every clean tape you play afterwards picks it up from those same heads. One mouldy tape can quietly infect an entire collection through a shared machine. Isolate it, and either have it professionally cleaned or say goodbye to it. Do not gamble your good tapes and your VCR on one nostalgic afternoon.
Hold tapes by the shell, keep your fingers off the exposed ribbon behind the flap, and do not force anything that resists. Every so often, run a proper VCR head-cleaning tape through your machine to keep the picture crisp and to stop grime building up on the heads. A clean VCR is a happy VCR, and a happy VCR is kind to your tapes.