Let's see. How about starting with the equipment. I say you want to spend some money on good input and output equipment. If your scanner isn't up to par then your output can't be that good either. Crap going in is crap coming out. If you plan to print, look for longevity, reliable equipment and high quality prints to compete with outside print sources. I wouldn't say that was a first investment though since you can get prints made from CD from an outside source however you will have problems in color management. I'd also recommend a graphics tablet but I have seen some impressive results from members using mice.
If you spent the money to get top of the line photo editing software, spend the time to learn it well. It will speed your productivity and quality of work. Look for useful techniques that aid your specific line of business. Search the net, there are thousands of good tutuorials free for the asking. The more you know the better you will be.
Advertising.... I would say, start with the source you refer to when you want something. The Yellow Pages. It's not cheap but it will get you calls. How you handle those calls is up to you. For me, I just try to be myself and if I think I can help them even if it's not going to put bucks in my pocket I will do so. I find alot of people respond to someone whos not out to play used car hard sell person. Trade referal services with other companies such as videographers, conservators and they will refere you. I get alot of calls for services that I don't perform so I recommend some who do and vice versa.
Finally, when you meet the people be open and friendly and know your business and they will respond to you as a professional but also someone they would trust.
And don't under estimate your services or people will think that's all your worth. That was good advice I got from Ed Ladendorf.

Best of all, enjoy your business and it won't feel like work.
DJ