You may or may not want to have a separate checking account and credit card. If you business gets large, then that can make accounting easier. But as long as it is small, then so long as you maintain a separate Quicken register for your business, then it doesn't matter whether you co-mingle your business money into your personal checking account and credit cards. Intuit also makes great tax software so that you can do your own taxes. These are easy programs to use and can handle all but the most complex of tax returns.
Many artisans have trouble pricing their work at first.
If you are new and unknown in the marketplace, then you will have to go through a disciplined process to determine fair pricing. Start out by figuring your costs. With those numbers calculated, you can determine the minimum price. On top of this, you have the choice of adding in a premium for artistic merit and reputation. All this may take time to build.