Tee-nut installation is not difficult if the correct drill bit size is used. For 1/4" tee-nuts, use a 5/16" drill bit. For 5/16" tee-nuts, use a 3/8" drill bit.
The tee-nut should be installed at the top (upper) surface of the wood so that a screw or bolt being inserted into the wood underside will keep the tee-nut tight to the wood surface providing strength. Some amount of hammer space is required above the wood, so that the tee-nut can be hammered down into the wood.
To install Tee-nuts, finger press Tee-nut until the large flange containing the gripper points touch wood. Then hammer in until flush.