Best?... there isn't one.
If you need a beginner lesson though,
PPC Coach :: PPC Marketing Training might help you
Yep. Something like this can help with the basics.
But after the basics, the best way to learn is do it yourself.
1. Identify the offers you want to promote.
2. Identify the top people/companies promoting that offer through ppc
3. Identify what terms they're using to drive traffic (SEMRush is a good way to get ideas for this. 14-day free trial should be enough to get you going, but you can find guys on fiverr that will set you up as many free trials as you want for $5 bucks a pop if you don't have the cash to plunk down for a $70 subscription right now. Or you can just test the serps yourself and see who's running ads for which product/search term combos - less expensive, more time consuming, but will probably help you get a better handle on things initially).
4. Imitate what those campaigns are doing to help identify the most profitable terms and ad types.
5. Improve on those imitation campaigns.
No matter what you do, you're going to need a bankroll to test. It doesn't have to be huge, but it has to be enough so that you can get some decent data and a general idea of what's going to work and what isn't.
Imitating successful/top campaigns can help keep your initial bankroll relatively small and help you start generating revenue so that you can try new things and improve your campaigns.
None of this will be that difficult, but you'll have winners and losers. Hopefully you hit some winners before you find the losers. At the end of the day, a solid PPC campaign is all about doing your research. Research the product, research the market, research the competition. Then imitate, analyze, improve (in other words test shit).