Solo trip NYE in europe

Sorry to hear about your cousin's experience. I've just been researching the "Carnival of Cultures" festival in Berlin in June, and the website makes it look like a giant Samba party. But there are (fill in the blank)-holes in any country. Berlin is the least expensive large city I have experienced in Europe, and has a very vibrant youth culture.

You can buy a Caipirinha in any bar in Switzerland. It is a very "International" country, but the price of everything is outrageous.

In the end, Italy is probably the best. Every Italian's dream is to retire to a beach hut in Brazil, drinking Caipirinhas and watching the girls walk by.

I've spent the last 4 NYE's in Paris, Paris, Orvieto, Italy and Amsterdam respectively.

Which country should i spend NYE: France, Germany, Switzerland or Italy?

You Should spend NYE in Paris. They have a sizable Brazilian population. I know for certain (and maybe you are not interested in this) there is a Brazilian style Reveillion in Paris Check this site the closer it gets to NYE.
https://www.bonjourbrasil.com/

Or spend it in Orvieto Italy. They have a well attended live music festival (attended mostly by italians) called Umbria Jazz Fest Winter
http://www.umbriajazz.com/ from December 26 - January 1.and fireworks at midnight on NYE by the Duomo there. This is a good way to practice your Italian language skills.

Where should i go to meet some nice and friendly people?

I am Not sure what you are asking here. You want to meet friendly people on NYE or in Italy during your stay?
If you mean NYE go to a club where other Brazilians are. it is easier that way. You are more likely to meet someone that speaks English or Portuguese in Paris than in Italy I think.

Any tips for my solo NYE and solo trip to italy?

Pay attention to buy or reserve your ticket for any NYE club party etc. These always sell out
My only advice for solo trip to Italy (and this applies to anywhere you go) Pay attention to your money in your pocket and your belongings. Secure them in some kind of way.

Berlin has the most famous and biggest NYE party in Europe, so that's an obvious answer, however it's SO big that it might be a real pain in the ass to get a decent hotel room and attend.

Germans are not nearly as friendly as in Brazilian culture, but Berlin is an extremely international city, with expats from every country imaginable living there. You hear as much English on the street as you do German (if not more). It's also very young, cutting edge, and hip.

One thing to keep in mind about New Years in the Germanic countries is that they're quite wild. All manner of fireworks and firecrackers are sold in nearly every shop in the days leading up to NYE, they start going off at nightfall, building to an insane crescendo right before and after midnight. I love it, the Germans really let down their hair and party big on NYE, but I know some people, including Germans, who find the scene to be too much and a little dangerous (I've been hit by stray bottle rockets myself) and prefer to attend a private party or stay home rather than take part in the scene on the streets. Public drinking is not just legal but exceedingly common on streets on German holidays. Something to consider.

Any capital city will be a great experience, and every capital city will also have other Brazilian and English-speaking expats if you want to ring in the New Year with new best friends. Look on Facebook for expat groups in any city. Hope this is helpful!

Since you are worrying about costs of travel, here are two basic sites to help your research:

www.seat61.com -- how to ride all the railroads.

www.skyscanner.com -- good for the one-way discount airlines that flourish in Europe.

You may find yourself taking weekend excursions with new friends (I hope so). I will leave it to them to describe inter-city buses since I prefer the comfort of trains. In any case, the rule of thumb is that last-minute fares are the most expensive.

Mom probably is footing the bill for some or all of this. Why not spend New Year's Eve with her, dining at someplace special. You can party-hardy when you get to school, especially since you will be legal to drink.