Once you have some DNA Points, click the small red icon at the bottom left of the screen..
This will bring you to your virus overview, displaying important information about your virus such as rate of infection and how many people have died because of it.
For now, go ahead and click (Transmission) at the top right. This screen holds various hexagonically linked "Traits" for you to spend DNA points on.
To begin with, go ahead and spend some points in the "Water" traits.
This will significantly increase the rate of which your plague spreads to other humans. Spending some additional points into the "Airborne" trait above is also a good idea.
"Eventually, your virus will very rapidly and suddenly spread to other countries. When this happens, you'll receive red DNA bubbles. As the orange ones, they give you DNA points when clicked on.
"Soon, you'll have to zoom out your view to cover the entire world as infected boats and planes will soon start to spread to every corner of it.
As you buy two different traits in close proximity to eachother, you'll get the exclusive right to purchase a "parent" trait. In this case, after mutating our plague to cover both air and water, we can spend additional points to make things such as waterfilters in waterworks or air-filters in conditioners be completely useless against our bacteria.
"After a certain point, your plague will also start to "mutate" itself. In this case, our plague starts to appear with the "Rash" symptom for the infected ones.
Hurry and go to the (Symptoms) tab..
And double-click the "Rash" trait and then click "Yes" to "De-evolve" this symptom.
Doing this will score you not only a much lower visibility to your virus but also bonus DNA points.
"Continue to watch the progress of your virus. Generally, you want to be careful with spending DNA points as too much will leave your virus with little material to later grow lethal with.
If you've followed my instructions and removed the symptoms, your plague should spread like a wild-fire with noone being the wiser.
You may get away with very small symptoms to speed up infection, like Cysts, which can burst and hurry up your rate of infection.
As your game moves along, there will be natural catastrophies occuring along with festivals. Both of these will usually work in your favor, disabling most hospitals or even an entire nation hosting things such as a "Festival of Love" where humans come in contact with eachother much more.
You'd especially want to watch out for the Insomnia mutation early on. It will be almost a dead-giveaway to medical practitioners that It's a plague doing this.
Natural disasters can also include impedement on research facilities. These are VERY beneficial to you as It hamsters the world's ability to fight back against you by developing a cure.
if you are having troubles infecting some parts of the world, go into the (Abilities) tab and start looking at possible countermeasures to this. Scoring any serious infections in countries such as Africa may require a point or two into the Heat Resistance trait.
Generally though, for bacteria, you want to level up the Bacterial Resilience trait as It benefits protection from all climates.
If trouble is find in richer countries such as France, Germany or Sweden, a point in Drug Resistance can do wonders. Evidently, you'll need to develop this entire drug resistance tree to become less suspectible of a cure being developed against you.
Eventually, your plague will have infected every person on Earth (All Hail Portforward) and so starts the time where you begin to kill the population off.
To do this, go to the (Symptoms) tab. It will be rather intimidatingly big at first as most of the traits initially have only infectivity benefits. But to do the shortest, "Lethality" string..
You need to build up to one square above the middle, grabbing the "Total Organ Failure" symptom, kinda important for lethality.
Once that has been chosen, go down to the right and pick "Systemic Infection".
Build your way to the "Hemorrhagic Shock" trait and you should be golden. Above Hemorrhagic Shock is Necrosis, If you want to kill them REALLY fast.