What is a good global strategy for trademark protection and how much does it cost?

I agree with Mr. Mincov; his advice is sound and stated quite well. I would also add to his advice that you should consider where your trademark is most likely to be infringed either because there is a lot of infringement in that country or because infringing is easy. For example, countries like China, Russia and Brazil have a bad reputation for marks getting hijacked, like Mr. Mincov described, and in those countries a large part of what makes that possible is that the first to file often gets the rights, not whomever has the use and reputation. So you need to anticipate which countries like that you will be operating in and file right away even if you have no use of the mark (i.e. not doing business) in that country yet. Those countries usually don't require use of the mark to obtain the registration. In other words, the "importance" of a country can be measured not only positively in how much commercial success it likely brings you, but also negatively as in which country could have the greatest cost to you if you lose your rights in your mark.
One of the most costly aspects of protecting your mark around the world is that trademark protection is territorial so you will need to file applications in each country in which you want protection and probably a trademark attorney in each of those countries as well. Most trademark attorneys maintain an network of international associates so if you consulted with a Japanese trademark attorney, he/she likely has associates in around the world to get you into whichever country you need.
Good luck.