Hm, this is kinda tough. I feel that after I wished, I'd think of other things to wish for...
1. Be psychic (includes clairvoyance, Telepathy, E.S.P. etc all of them^^) Then I could teleport all of the first nations unwanted food to third world countries and, bada boom bada bing, no more world hunger) (not to mention I'd be able to make a living tell fortunes and contacting dead loved ones^^) Also, inducing hallucinations, so people could meet their fav characters or dead loved ones, or enter their fav story.
2. End organized religion. Seriously, this is the cause of more disagrements and wars nowadays. Not ending religion, people will still be free to practice whatever religion they desire, but there will be no more segregation between religions like going to a mosque or church.
3. End prejudice. Probably not all at once, but speed up the process^^
Hopefully, once the world is all friendly and happy, we'll be able to cooperate and make as many scientific advancements as per needed with our growing population and climate concerns^^.
(Yeah, no world peace, we have to learn to achieve that on our own)
My three wishes would be : I would have 10 more wishes . The world would be healthy , People would stop polluting land/water and stop cutting down trees. and for my extra 10 wishes xd: People would be respectful , not be racist , stop killing animals , People who are poor would have a good life , unicorns in my house 4laugh , meeting my idols , i would have a good future , each person in the world would have fair money , people wouldnt be greedy and me having a awesome house rofl