Follow these steps:
1. Choose China as the first country to infect
2. When you collect 4 DNA, get Coughing from Symptoms (this helps spread the virus faster)
3. Once you have collected 9 DNA, get Water under Transmission; get Air with next batch of DNA collected (you'd need about 10)
4. Once you've gotten the first level of both Water and Air transmission, get Heat Resistance 1, Drug Resistance 1, and Cold Resistance 1 in the given order.
- with each evolving, it will cost an extra DNA to evolve on another thing. Because Heat Resistance and Drug Resistance cost much more DNA to evolve, it's best to evolve these to first
5. Get Genetic Hardening 1 just under Drug Resistance 1 in Abilities (this will help slow down the development of cure)
6. Get Air 2 and Water 2.
*at this point, you should be nearing Infected # of one billion. Once you've infected more than one billion with your virus, they will take notice of it and start working on cure.
7. Get Genetic Hardening 2, Heat Resistance 2, Cold Resistance 2, and Drug Resistance 2.
8. Get Extreme Bioaerosol between Water and Air in Transmission, then Genetic Reshuffle 1, 2 & 3
- now that you've made your virus infectious enough, you need to focus on fighting against cure development
9. Develop all three levels of Viral Instability under Abilities
10. Get Bird 1 & 2 and Livestock 1 & 2
Once you've reached this point, you have achieved all the abilities and transmission to successfully infect every person in the world. Now it's just the question of killing off everyone before cure gets developed.
11. Get Symptoms such as Paralysis, Coma and Insanity to help slow the development of cure.
When everyone is infected, you have to kill them off fast! Best way to do this is to evolve symptoms that have high lethality such as: Total Organ Failure.
After this, you should be able to eradicate humanity for good. Hope this has helped!