Get the dent out with a body hammer and dolly if possible and then use the bondo to fill the rest of the dent. The fillers of yesteryear were very bad for cracking, shrinking, and overall non pliability. Today is a different story with easy to sand fillers that are extremely pliable and durable. For small hail dents I suggest a 2 part glaze filler (evercoat from Autobody Supply, or tech 1 glaze from NAPA) will fill small dents with small sanding efforts. The primer coat and blocking will fill in all the imperfections, and for the beginner I suggest Dupont Sand and Fill which is reduced with Laquer thinner and is good for filling the very small dents etc. Thicker body fillers can be used, and are recommended for larger Above 1/8" dents, but are harder to sand. Black is actually an easy color to paint, but is brings out bad body work very quickly, and white or light colors hide it. It seems that with some of the info that you have been getting that not many people have actually painted or done bodywork before. I would also suggest getting a book and having patience, because bodywork is very laborious and tedious if done right.