For the guide and strategies, I will collect every written, video and other related stuff that I can and have them here so everyone can check it out. So far, here's what I have:
Strategy 1: Start on a relatively poor country but capable of transportation (airport or shipyard). Keep in mind that rich countries will most likely find a cure quickly so you must start off with the weaker nations and stay under the radar. You can pick somewhere in South America and from there increase you DNA points. Then start increasing the transmission by going to the disease at the lower left. Once you infect about one thousand or more people, you can make advancements on the disease's abilities and have it survive in extreme weather conditions. When you are certain that your disease can now infect at a rapid rate, then it is the right time to start making it lethal.
Strategy 2: For the virus, upgrade the first 3 levels of symptoms and start in India. Upgrade the transportation, air and ocean then resistance to antibiotics but only level 1 and 2. Prioritize maximizing other transport parts rather than upgrading cold or heat resistance. The sequence will is like: one upgrade to transportation of virus and one for resistance to cure. It will then mutate very quickly and it should be an easy win.
Update: Videos demonstrating some strategies on how to beat Plague Inc app will be collected and displayed in the playlist at the bottom of the article.
Strategy 3 (For fungus on normal difficulty): Start in Iceland. Upgrade the air and water twice. Upgrade heat twice and cold once. Upgrade drug resistance 1. Sell any mutations for DNA points. Once the entire world is infected buy total organ failure symptom which starts with coughing. Finally, upgrade more drug resistance to slow down the cure if you have any DNA left
More strategies, tips, hints and video will continually be added to this collection of game guide for everyone to see. Meanwhile, you can help us improve this Plague Inc walkthrough by discussing or submitting your own tips below.