You received some good advice from some folks, but let me offer my two cents - as background, I am a CPA in Texas and work for a large company, and I have also formed my own S-Corporation in Texas.
In addition to getting an assumed name license from the state (also known as a "DBA" form), you will also need to get a DBA form completed in Harris County (I believe Spring is in Harris county) - every agency wants your piece of tax revenue. That DBA form should be good for about 10 years in Harris county.
While the state of Texas will give you an identification number so you can pay your sales taxes they also want you to fill out the franchise tax form, which was revised last year into what is now called the margin tax; the margin tax is effectively an income tax based on revenues - unless you're making about $300,000 in sales you won't have to pay it, but you will still have to fill out the form. I caution you on NOT filling it out, as they will really slap you hard for not completing the form and penalize you monetarily as well as suspend your business license in the state.
Assuming you wish to incorporate (although LLC or LLP route is the same), you will need to apply for a corporate license and be chartered in the state of Texas. The last time I looked, that cost $315.00 as a filing fee.
You should also fill out a request for a taxpayer identification number with the IRS; you can get that from
www.irs.gov - like one of the previous posters mentioned above, you can use this number to be sales tax exempt at your supply stores for items you will be crafting or selling, but you will still have to pay taxes on tools you use in your shop.
Speaking of tools, yes, you can run through the cost of your tools on your tax return, but if you consistently show a loss the IRS will "pierce the veil" and determine this is a hobby vs. a true business and disallow your deductions. In other words, and as in all business ventures, try to make a profit. It is, however, a great way to purchase great tools at a discount (sales price deducted from your tax return gives you a discount at your top tax bracket).
This is all pretty high level advice, and reading over this I have assumed you will know how to look. If you're serious about this venture, and you have any questions, I would recommend spending a couple of hundred bucks with a tax accountant to help you. If you have other questions, please feel free to PM me.
Good luck!
Michael