there's no better teacher than experience i guess. but, we should always be taking educated risk so that at the end of the day we'll definitely know what we did right and wrong.
Tools... You don't need them. That's right, fuck tools. I purposely don't use them, at some point in the future I might look into some that help me automate shit but TOOLS are not going to be the difference between a profitable and unprofitable campaign, your brain is. The only tools you need are free, and that's Google's line of tools (Mainly, in fact almost solely the Google Keyword Tool)