Article originally found in sc4ever.com
Achieving such results as the title suggests is actually relatively simple, just plaster your city with trees. It's relatively inexpensive for what it does and will do all three things mentioned in the title. I started placing trees and all my manufacturing and dirty industries immediately converted to high-tech. And if you're feeling particularly lazy (as this process can be very tedious), then use that cheat to get full God mode back and use the tree tool. Note: If your High-Tech demand is still high, but the rest of your non-High-Tech industries aren't converting, then just keep plastering the area with trees, it seems the more active and intent you are on placing trees, the more likely it is that High-Tech industry will develop there. The increase in trees also server to expand the size of commercial and residential development as well, although the effect is not as profound as it is on the industrial sector.