To directly control the world requires a fundumental re-ordering of society, taking over the authority of established government. To do this I feel you must evoke powerful fantatical feelings amongst the masses, strong enough for them to abandon their previous lives. This requires the adoption and pursuit of a fantatic idealogy; without a compelling ideaology I believe resistance will be too great for you to gain substantial power.
Tapping the power of religion is, I feel, instrumental to developing masses of loyal subjects. Only a vibrant religious revolution will have the strength to topple established ways of life across many nations. You could appeal to other ideaologies (social, green, freedom, technological utopia) but ultimately I feel these lack the raw power and universal appeal of religious fervor.
Without a substantial opponent aware of or possesing supernatural powers, I'll start a religion. Perhaps claim to be the Messiah of Christianity or Islam, or perhaps just use magic to openly perform miracles and deliver divine wrath. Spells with obvious visual manifestations should quickly allow me to amass millions of believers and start a holy war to clense the world of infidels and bring on the days of final judgement. That is, assuming no god will smite me down and no MIB will use some wicked-fu on me.
With the MIB and other opposing supernatural forces in the world, this option is no longer viable. Instead, I'll institute a mystic cult of terrorists making heavy use of charisma-enhancement, enchantment, and divination spells. I'll spend several years growing the cult's networks and cultivating personal loyalty, secrecy, and fanatic apprentices. Dominate and charm person will be essential to garner financial support from rich buisnessmen worldwide.
Then I'll use it to instigate terrorist attacks against a chosen weak country, using cultists from within that country's oppressed majority. Its retaliatory measures will win me more advocates, and after a few years of pressure and some divine miracles (making heavy use of protection spells, divinations, and teleportation to avoid pursuit) I should be able to garner enough influence for it to be possible to overthrow the government in a massive "Day of Reckoning" and install a shadow government with sufficient political clout to maintain power. A few greater-teleportation spells, planar bindings/allies, and good timing should suffice to kill the parliment and government while announcing a new one. I'll try to arrange mystic elements, such as illusions manifesting in the news' room proclaiming the new divine reign, rain suddenly stopping as the parlament is overrun, and so on.
Then cultists and spies will be used to cleanse the land of dissidents, while money will be used to support my cult and terrorism supporting it across the border in far-away lands, restarting the cycle.
Concurrently, I will dominate-person key leaders and military/secret-agency staff in centralized countries. Using their clout, I will begin "cleansings" that will culminate in having those countries' leadership in my hands and later the conversion of its religions/doctrine to my cult.
Once enough countries are controlled by my Holy Host, I will build up a sizable army while encouraging cultists in the remaining world, and attempt to cripple the economy of the remaining nations. Ultimately, a military showdown will be invevitable (possibly several showdowns), in which divinations will be paramount.
Using planar binding to bring forth demons that fit my cosmology to smite down the "heathens" in front of cameras should serve well to bolster my cult in all lands, even if these attacks will fail.
Clairaudience or Scry/teleport teams to take out key installations/persons are also critical (it's better to leave a powerful bomb then to use attack spells). Geasing/dominating key enemy officials through scry/teleport may be even more useful.
A contingnet raise-dead can have a drastic effect, especially if it's orchestrated to mimic cult motiffs of resurrection. So would healing spells and raise dead in general, including remove disease.
Discern Lies and Detect Thoughts (etc.) can be used in interrogations and interviews, to ascertain loyalty of would be henchmen.
Nightmare may be useful towards making true conversions for those that have doubts.
Tongues will be used to great effect when making speeches - it's always better to speak to people in their own tongue, especially when you make clear you've never learned it and what you're saying is the divine speaking through you.
Multiple other spells can be used as well, if appropriate mythology is linked to them. For example countinual flame can become a holy icon of god's eternal brightness. (If the MIB/others have the ability to dispell these, however, you don't want to use a permanent spell.)
At all times dominate person spells will be used to control the key leaders of local groups of cultists/terrorists, and charisma-enhancement, nondetection and anti-divination measures, and divination spells will be in heavy use. Always have a contingency set up to save you. At least initially, use a terrorist-cells organization to isolate and hide yourself and your resources; that should protect you from the MIB until you become too powerful for them to take you directly except through magical means. (Cultivate fanatical apprentices to help you deal with that.)