Pay Your Self to much from the start
When you're just starting your business it is important to keep track of all your spending. The biggest one is going to be keeping food on the table for yourself. While it is very tempting to see money start coming in and wanting to get personal things for yourself just remember there are slow sales weeks and your bills always need to get paid. Don't let one bad sales week or month ruin your cash reserves, you might need to live on less then you'd expect the first year of your small business to ensure continued success.
Don't Keep Over Head Low
As with keeping money in your bank from not over paying yourself is important so is keeping all your businesses bills and expenditures low. You don't need to have the best of everything but determine what is a must for your business. If your business relies heavily on foot traffic make sure you have a good location for your business to succeed, this may cost more than your other bills but it might be the most important part of your small business and deserves top priority if you want to succeed. On the same note if you're an online business you might not need a high traffic location and instead should focus on keeping your shipping bills low to maximise your sales profits
Don't Want to Put in the Extra Hours
If you've taken the leap into owning a small business you should expect to work long hours. The days of a Monday through Friday 9-5 might be in the past but that's not why you decided to work for yourself. Answering phone calls, emails and working through the night might not be needed every night but there are times you will need to put your head down and get something done whether you want to or not. Owning a small business or even a larger business might mean 80+ hour weeks so determining when to get an employee or two is a very tricky balance because you also want to keep your overhead low and an employee is a far more expensive than what meets the eye.
Don't Try to Out Source All Your Work
Whether you think you need some help to get all the work done or you're trying to avoid working long hours an employee can be both a blessing and a curse. If you hire the correct employee he can save you countless hours and work and make you thousands of dollars. However if you have more than you need or an unmotivated employee he might cost you more money than he is worth. If your small business is an easy idea or doesn't require much capital and know how to start you might have to worry about him copying your idea and trying to start his own “better” business on the side. There is a fine line to draw between a great hard working employee and someone who isn't challenged enough and will take your idea as his own. Be very careful when looking for employees as to make sure you have enough work to keep them busy in the long run or make it clear they're just a temporary employee.
You're in it Just for the money
The biggest problem is trying to start a business purely for money. I'm not saying you shouldn't go into it looking to make a profit but if all you're concerned about is making money your intentions will soon be seen and that's not good for anyone. Think about why you wanted to start this business and get back to what you use to enjoy. If you really like music and you open a music store you're going to be far more involved than if you tried to sell music lessons to the highest bidder. There was a reason you decided to go out on your own and try to do it yourself whether you thought you could do it better, there wasn't a business like it in your town, or you were just tired of making someone else money with your unique skills that weren't getting noticed or properly compensated. Running your own small business is a lot of work and you should go into it for a reason because you're better at what you do or have a passion for doing it not because you think it'll make you some easy money or it will sadly fail.