1. Not promoting yourself. This is an area where you cannot be timid or shy or modest. Think about your favorite products and services. How were you first introduced to the businesses that provide those products and services? Most likely it was shameless self promotion. Television commercials, magazine ads, and social media marketing are designed to make products and businesses shine. They never emphasize the negative. They sell you the positive. This gets you to try the product and see for yourself if it lives up to the hype. If it does, you go back. You should think of your studio the same way. Sure, you won't always be doing the best work of your life. But sell yourself using the best work of your life. Then live up to the expectations of the client. They will see for themselves that you live up to your self promotion and they will come back.
2. Worrying too much about what everyone else is doing. This is the biggest waste of your time. You will only succeed in the saturated photography marketplace if you stand out from the crowd. How can you set yourself apart if you spend all of your time and creative energy trying to be like the studio down the street? You can't. The time you spend looking at the work of others on Facebook and Pinterest would be much better spent with a sketchbook and your camera, coming up with your own ideas and finding your niche.
3. Not knowing what you are worth. Do not, I repeat, do not under-price yourself. You cannot be successful if you price yourself based on an average of what every studio in town is charging for similar services. You have to take into account what it costs you to run your business. Your rent will be different than another studio's. Your product costs will vary. Your skill level is yours alone, and the product you offer should be unique. Your prices should reflect all of these factors. And please don;t think that you should price lower to get people on the door, or do giveaways on Facebook. This sets a bad precedent and makes it hard to retain clients when you raise prices in the future. It is going to take some time to build your client base. Make sure you are attracting the kind of clients you really want right from the start.
4. Getting stressed out and overwhelmed and not getting help. It's okay to feel those things. We all do. Running a business is hard! The problem is when you don't get the help you need to get it back under control. If it's finances or taxes get a good accountant. The money spent is well worth it for the peace of mind. If you need an assistant get one. Maybe it's your mom or an older child, just get one. Whatever the problem area, there is someone out there that specializes in that thing. Find someone you trust to help you through the tough parts. You may just need the help temporarily and it is not a reflection on your abilities. It might just make the difference in your success or failure.