Hi Jessica! Welcome to the wonderful world of photography! I'm sure your passion will take you far

So what comes first after a few cameras, lenses and an account on OSP? Definitely a lawyer. Before you start doing anything, you want to make sure you're set up properly and legally with the federal government (incorporation and the IRS), your state government (sales taxes and fictitious name), and your county (occupational licenses and tangible personal property taxes if applicable). For maximum protection and tax benefits, I highly recommend being a subchapter S corporation, but talk to your attorney and CPA and get their advice (IANAL

). But this is all very important...if you don't register properly with the IRS, you can find up being liable for taxes on your entire
gross instead of your profits! Eeek! That would be an oversight of the pants soiling variety

Your attorney will also be able to help you with contracts. Also, don't forget to get liability insurance (in case you accidently injure somebody on the job) and equipment insurance.
Prices come next. Figure out your exact costs of business for whatever kind of jobs you'll take on. Are you looking to get into weddings? They are tons of fun

Or portraits? Figure out how many weddings you want to do a year, and add up ALL your costs. Equipment, taxes, insurance, phone, internet, professional fees, marketing, advertising, office supplies, etc etc. Divide that by the number of weddings you want to do per year, and that's your base cost for showing up at a wedding. Add to that the cost of goods sold per wedding (the cost of whatever's in your package. So the cost of the prints or album or whatever). Now you have your break-even number. Shooting for anything less than that and you're losing money (Old photography joke: One photographer says to another, "Man, I shot 50 weddings last year and lost money on each one!" "Well, what are you going to do differently this year?" "Shoot more weddings!").
Now figure out the time involved for each wedding. First, give yourself a decent estimate for the number of hours a week you'll need to spend doing general business-related things that aren't tied to any specific job. Marketing, training, bookkeeping, idling on OSP, networking, making samples, etc etc. Multiply by 52 and divide by the number of weddings you want to do per year. Now estimate the number of hours it takes to complete each wedding job, from the time you pick up the phone to the time you deliver the finished product. So, add in, time spent talking on the phone, answering emails, the first consultation, processing the booking, consultations before the wedding, gear prep, travel, shooting, downloading, sorting, editing, uploading, proofing, designing, printing, packaging, delivering, etc. That's your time spent per wedding. Add that to your general "time overhead" and now you've got your total time investment per wedding. Figure out what you want your hourly wage to be before taxes, multiply that by the number of hours it takes to do the job, and add that to your overhead we figured out in the last paragraph. And there you go, that's the price you charge for shooting a wedding

Obviously, those are estimates, and can be influenced by things like reprint sales, etc, but it's a good start

Once you've got all that, go for the naming/logos/branding aspect. Doesn't make much sense to print up business cards or get a website when you don't have a name, logo, or color scheme, eh?
Then the website...check out Big Folio. They make great sites for reasonable prices.
Advertising Dos and Don'ts...well...do advertise, don't not advertise

I'm sure if you search through the forum you can find a lot of great advice on advertising. There's the web, local magazines, bridal shops, bridal shows, networking with other vendors, building a referral network with other photographers...there's a billion ways to go about it, and what works for someone else may or not work for you. You'll just have to use your best judgement on this one

Best of luck, and, once again, welcome!
Matt
P.S. wow, that was long. Good thing I type 100WPM...