Ok, I have never made a wedding cake but have had several requests and I always chicken out.... but a recent request has me teetering back and forth whether to just go for it--- I have to start somewhere right? 
so as far as procedure goes for consultation:
Ask-
how many
their budget?
flavors
date(obviously)
colors
what else?
Also, what about deposits and contracts?
AND,.....this one REALLY worries me,... what about summer weddings...as far as humidity and fondant,gumpaste decorations(drying and staying dry!) storing the cake before delivery,...... oh, and that reminds me what about the whole delivery/assembly process?
I'm trying to overcome my fear and self doubt but I'd also like to be prepared for possible obstacles
Definitely how many. How many they've invited, and how many they're expecting.
I wouldn't ask their budget. Make sure you are firm in your pricing though. Think of prices and answers for everything you can (what if they want you to cut the cake, are you willing to do that?, etc)
Flavors are also something you present to them. If you want to offer them the chance to create their own, I would charge extra for that. You know what recipes work, and how they are going to taste, you don't want to use a wedding cake to experiment with flavors.
Date (Obviously 
)
Ask what color scheme she's leaning towards, and then offer your suggestion as to what you can do to compliment/match that. Use this to your advantage to "push" designs that you know you can do well, and that would look good.
You definetly need a contract before you even meet with the b&g. Spell out in-case scenarios (cancellations, change of dates, etc). Also spell out any delivery charges, extra charges (putting fresh flowers on, cutting, etc) and when deposits/payments are due. Usually it is wise to get a deposit (% depends on when the wedding is, but 20% is good) when they are booking you. This saves their date and allows you to buy any supplies you may need to start on the cake decorations. Balances should be paid in full at least two weeks prior, but I like a month, and that should also be the cut off date for all changes (shape, flavor, and even servings)
If it's outside, you need to prepare the b&g for possible mishaps, and urge them to put the cake inside if possible. As far as for your sake, gumpaste once dry would be find outside, no melting. Fondant will get gummy, and buttercream will melt (obviously), but if you're indoors in ac, you should be fine.
You have to figure out what the average cost to deliver a cake in your area is, and charge accordingly. Also, you can charge set-up, but I would include that in your delivery. Make sure you specify what set up means in the contract. Sometimes when you say "oh yeah, I'll set up the cake" people think that means decorate the table, arrange flowers, and a lot of other stuff. Make it clear what you will and won't do. Give your self at least two hours before guests arrive to set up the cake, if possible. This gives you enough time to fix minor "injuries" and make sure everything is the way you wanted it.
It is stressful the first time, just like everything else. The consultations definetly get easier, but I can't say the same about deliveries...they become tolerable 
Hope this helps a little...take baby steps, and if you make a mistake, just make sure you correct it the next time. Only way to learn! I can't think of anything else, but I'm sure other's will help too. Best of luck!
When I did my first one they were completely aware that it was my first cake. Against the advice of my family, I gave them a giant discount on their cake because I was nervous about it being my first.
I always start out by asking if the bride has any ideas as to what she wants her cake to look like. It's really helpful if she does, but it's fun to go through the design process if she's not sure.
With those that don't have a clue, I start off by flipping through cake books and asking simple questions like if she prefers columns, a cake stand or the stacked construction. Then I move onto what shape she likes, is she wants flowers on the cake (sugar, artificial, real?), fondant or buttercream. She'll also need to pick cake flavors.
As far as deposits go, I always make sure their final payment clears the bank at least two weeks before the wedding. Brides tend to get stressed out and forgetful as their big day draws near, so I like to get it out of the way.
Gosh, this was long and I could ramble on forever...
Just go for it! Good luck!
don't stress over heat. Brides have been getting married for centuries in the summer months and everything usually turns out fine. Not all weddings are outdoors and most if not all reception sites are nice an dair conditioned.
the only thing I would respectfully disagree with on the above posts is "buttercream melts (obviously)". Not "obviously".... Maybe "sometimes". Mine doesn't. I've never had a melting in 25 years. If you use a good crusting BC, you'll be fine. But everything else already said is excellent advice.
As far as all of the business portion, what are you doing for the cakes you are making now? Do you have some kind of contract? Deposit policy? Delivery fees or agreements? If so, you just expand that.
A wedding cake is just a bunch of little cakes all stacked together. Don't panic .... don't stress. Just take it one step at a time.
We CC'ers are always here for your questions as you move into wedding cakes!
Well, that was my thought,.."..many weddings ARE in hot months,so if I'm going to do this I better get over that "
Almost all my cakes now are fondant covered so they can sit out(I've only ever done one cake in the summer-and it sweated like crazy) I have NO idea how to store various caovered cakes in the summer heat.....
I've only ever sold to family and very close friends -no contracts/agreements...just wingin' it--but I'd prefer to become more professional 
I do like your comment: "A wedding cake is just a bunch of little cakes all stacked together."---that makes me feel a bit better about tackling my fear 
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