1) Figure out who you are selling to and what problem you're solving for them BEFORE you build something. It's very easy to fall into a routine of building the best software ever while forgetting you need someone to buy it.

2) Banks will loan you money when you don't need it and won't loan money when you do need it. Apply for a loan or line of credit when you're flush with cash in case of a rainy day.

3) Running a business is a different skill than developing software. Be prepared to learn a lot of new skills.

4) Don't hire too quickly. Payroll + benefits can eat through profits like crazy in a software business. The counter-point is that a good salesperson will bring in far more revenue than they cost in salary and commission.

5) Know your numbers. You should have good accounting records and know from week to week if you are on track or slipping.

6) Don't hire a 'marketing' firm. They will charge 10's of thousands of dollars to ask you questions like 'What do you think we should do?' and then feed it back to you. If the product is positioned well with customers, you know more than the marketing company ever will.

7) Don't let a single customer account for more than 10% of your revenue. If that customer leaves, you'll be in a painful situation. It's difficult to do this at first but it keeps you from chasing a big fish to the detriment of the rest of your business.

8) A good reputation and word-of-mouth is better than buying the #1 spot on Adwords.

9) Figure out how to sell again and again to the same customers. A one time sale makes means a high cost of customer acquisition. Once the customer likes your company you should see what complimentary products and services you can sell too.

10) Once you've had a taste of the freedom (and stress) of working for yourself, it will be very difficult to go back to a regular job and work for anyone else.