Maybe a general rule is sufficient since most bulbs are pretty hardy. Here are the general rules -
Tulips are planted about 8 inches deep
Small bulbs such as crocus and hyacinths are planted 4 inches deep
The planting depth is measured from the bottom of the bulb. So, 4 inches deep means make the hole 4 inches deep rather than put 4 inches of soil on top of planted bulbs.
Bulbs are planted nose up and basal root plate - the flat part on the soil. If you have sticky clay, you can add a bit of drainage material under the bulbs. I've used gravel from our driveway though I've read that sand works as well.
|Bulb trench - Rochestergardening.com|
Unless rain is expected within a couple of days after planting, water the bulbs to settle them into the ground. That way the roots can get started.
It is also a good idea to add some mulch to stabilize the soil temperature so the bulbs are cozy. Three inches of pine needles or other loose material is good. Do not use un-chopped tree leaves since they compact over the winter and could make the bulbs rot. If you can run the lawn mower over leaves, they are less likely to cause problems.
The exception to the mulching rule is the really early bloomers such as our February blooming crocuses.
As for spacing, it depends. Most tulips are annuals here so you can plant them as close together as you want to. Bulbs that will survive and multiply like hyacinths and daffodils, should probably be spaced a few inches apart so they have room to do their thing.
Here's are a couple of charts from BHG.com - visual aids help!
chart from Tulsa Master Gardeners
Usually bulbs come with instructions but if you have
any questions not answered there or here, ask away.