At its best:
Fill each hyacinth glass with water to just below where the bulb’s base will sit, then put the bulb in place. Make sure it doesn't touch the water, but sits just above it.
Once the main green shoot is about 7-10cm tall, move the glass into full light and watch the flower gradually develop.
Buy ‘prepared’ bulbs, not the cheaper garden hyacinths. Prepared bulbs have undergone special temperature treatment to initiate flower bud development.
Turn the glass around by a half-turn every day, to prevent the plant growing towards the light and toppling over. Top up the water as necessary.