Your bass drum heads are usually at a much lower tension than any of your other heads. This has the effect of making the batter head more prone to denting. Add to this the fact that the beater hits the head in exactly the same spot every stroke.

Make your heads last
To make your batter heads last longer, you may want to cut out a small circle of mylar from any old head (an undented one), and glue it to the head at the point the beater strikes. Use a mild glue like Bostik Clear, a contact or polystyrene glue will eat into the plastic.

The Hole Truth
A hole in your resonant head changes the resonant frequency of the drum, and affects how the heads vibrate and how the drum sounds. A drum is designed to operate as a closed system. Only make a hole in your resonant head if you need to put a mic inside the drum often, make this hole as small as possible, no larger than 6", and off-center. Consider having two resonant heads, one ported, one solid and then use the appropriate one for the gig.

Preparation
Remove the old heads. Clean  the hoop and bearing edges, removing dust, stick debris, and any build-up that is found. Cleaning and polishing should be done now, as there are no tension rods or hoops in the way. Do not use any liquids.

Fit the heads
Place the head onto the drum and spin it around the bearing edge to ensure clean contact. Tighten the tension rods until they make contact with the hoop. Do not tune yet. A good thing to look out for at this point is damaged tension hooks, as they can affect the tuning of the drum. Replace any faulty hooks immediately.

Batter Tuning
Put the drum flat on the floor. This deadens the resonant head, allowing you to isolate the batter head. Also with a large drum such as a 22" bass drum this negates the possible flexing of the drum due to it's weight.

Following the order in the diagram here, begin tensioning by turning each key rod a quarter turn at a  time, until the lowest possible pitch the head will resonate is reached. Basically, tune until the head stops "fluttering", but no further (this will be slightly higher for a single ply head than a double). Tap around the circumference of the head listening for high and low spots and correct accordingly.  

This is as far as you need to tune your batter head. This is a low pitched drum remember, and to get the low note required needs a very loose tension. Tighter, and the drum will click more, but be unable to produce as low a note. Looser and it cannot produce the note at all.

Resonant Head
If you tune the resonant head in the same fashion as the batter you will either have a similar note (if your batter is also single ply), or slightly higher (if the batter is a twin ply). With both heads tuned identical, the drum will "boom" more, with a longer sustain, and be slightly louder. With the two heads each tuned to a slightly different note, the drum will have a "tighter", more controlled sound.

And Finally...
Place the drum upright, in the playing position and check the tuning. Thinner shelled drums will often go out of tune now (due to the drum flexing from the weight of itself), so make sure to adjust again in this position.