Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington and Wyoming have no individual income tax.
AK, FL, NV, NH, SD, TN, TX, WA, and WY have no individual state capital gains tax.
Setting up a "C Corp" might not necessarily be the best way to go as you will likely be taxed at a corporate rate. If you are an individual, an LLC and filing as a sole proprietor and straight pass-through on your income might be the best way to go. From my understanding, C Corps are subject to double taxation - you're taxed at the corporate level and again at the shareholder dividend level. C Corp shareholders also can't deduct losses on their personal income tax filings (but S Corp can I think).
That's my understanding, YMMV. Best to consult an accountant.