Let's look at wedding photography.
1. You need experience. You don't get the 'Joost and Amor' wedding photos by just snapping away. (maybe a bad example). Most good photographers have ghosted or was the 2nd photographer at weddings. And remember, if you did the family photos, you are NOT a wedding photographer. If you own a DSLR, you are not automatically a wedding photographer. If your cousin takes nice photos, he is not a wedding photographer, unless he does it for a profession
2. It is the most stressful photography around. You have a few things to consider. Remember that it happens only once. You missed the kiss, rings etc., you can't stop and ask to take it again. You have a stressed out bride, bridezilla mother-in-law, bride's mother from hell and that doesn't even include aunty Jackie with her fancy 12MP cellphone. And yes, we haven't even started with the photos.
3. The photos. You need lots of memory, lots of batteries, a few flashes (the onboard flash doesn't cut it), a DSLR that can handle high ISO, if you want to get the natural light mood, tripods, a reflector, a slave and a few other things. The photos include the pre-wedding photos, the ceremony, the 'family' photos, bride / groom photos and reception. Then there are everyone with P&S, cellphones, iPads and Smart TV with build in cameras to screw up the photos.
4. Style. Yes, there are different styles. The traditional shoot, the journalistic and one I just made up, called the I-am-trying-to-out-photo-my-competitors-with-this-extremely-elaborate-setups-style (ego of photographer may have an impact on this).
5. Clothing. If you arrive with jeans and a T-shirt, you are doing it wrong. Unless you are going to a hippie wedding, but then, you might not be allowed to take photos as a few people may be incriminated using illegal substances. Professional and comfortable. Remember you will be on your knees, on chairs, doing positions that the Kuma Sutra would declare as impossible (note, not with the bride, that will lead to more problems)
6. Cost. You get what you paid.
7. Food. Don't bother. You won't eat or drink anything for 6-7 hours.
And that is the first 20% of the wedding photographer
The 80% include:
Editing.
Editing.
Editing.
Editing.
Editing the brides bulges (because she wants to look like Beyonce)
Editing the mothers (because they want to look like Beyonce)
Editing uncle Johns Purple suit to black (o, yes, this has happened at a wedding before)
Then the selection of the photos by the couple. O, crap. Everyone is a F#$#@n photo critic. The couple might be okay, but aunty Steve that took photos with the Pentax 1000 in 1974 while on holiday at Hartenbos is a F%$#%n expert
And getting the last payment...........
So, yes, wedding photography is a great money generator. It is 'easy' and 'everyone' can do it. (note, sarcasm)
And this is my honest opinion of wedding photography. Don't do it unless you are willing to commit and build up experience. Like all things, it takes practice. I avoid weddings, unless it is a special request.
Conclusion: Don't do it, unless you are good at it