First priority is continuing the sharing. It supplies a steady stream of mostly willing hosts
When Elfangor lands, since I have no personal beef with him, and no reason to kill him outright, I take him as my host body. His memories allow me to fairly quickly find and take the "Andalite Bandits." Two will go to my most loyal lieutenants, Marco is given to Visser 1, and the other 2 are sent to the council of 13 to bribe my way up the ranks.
Loyal lieutenant #1 is sent to Africa with food and technology to "give" to the locals. Infestation will go quickly, and while the tactical advantage is not very big, it is yet another good stream of hosts.
Word of Africa's rapid advancement will reach the news outlets, where it is tied to my shell corporation. I suddenly have support from other world governments for my "good will missions" to spread out into other continents, focusing on the poorer ones. India gets the most focus due to it's large population, but I make sure not to ignore the others. Without the Animorphs foiling my plans, I have no opposition to any of my plans, and my humanitarian standing gives me access to America's leaders, who get infested. The Andalites are likely still not paying attention to my operation. I can start shipping bodies to the homeworld and supply all of them with a body.
Hosts that won't be missed are shipped off world to do some menial labor, build ships and weapons now that we have the bodies to use them.
Launch a small overt invasion of a planet near the Andalite homeworld, while simultaneously shipping large numbers of Yeerks to Earth.
Start overt invasion of Earth, I have control of a large percentage of the population, and should meet with little problem resistance.
Set up breeding farms ala one of the bad futures shown in the series.
Send many troops to Leera to insure success of that invasion. Again, there are no Animorphs to get in the way and it likely goes smoothly. Likely pick up a few more Andalite hosts.
Tell the council of 13 of my incredibly clever plan of sending the newly captures Andalites in a few ships in an "assualt" on Kelbrid space.
Watch in glee as most of the Andalite fleet is destroyed by the retaliation strike.
(How many promotions have I earned?)
With the Andalites greatly weakened, launch an all out assault on them. Our human army is enough to overwhelm them with sheer numbers.
Retire in luxury on Risa, or its Animorphs equivalent.