For small bulbs:
Use a dibbler, these handy digging tools have a pointed end perfect for pressing a hole in the ground that is just the right size for a small bulb, and the hole can be easily covered over with your hand.
Medium to Large Bulbs:
Use a bulb planter. Generally speaking, these tools look like a drinking cup without a bottom, but with a handle on top. Press the planter into the ground, pull it out and you will remove a cone of soil. Drop the bulb in the hole, then brush the soil over the bulb.
Masses of Bulbs:
If you are planting lots and lots of bulbs, then use a long-handled bulb planter so you can work from a standing position – a faster, more comfortable alternative to crawling across your lawn. If you plan to plant masses of bulbs close together, then your best bet is to dig a broad planting hole to accommodate the mass of bulbs instead of making holes for each one.