Don’t try to see too much in one trip: stick to a region, like Sao Paulo, Iguazu Falls & beaches around Sao Paulo state. Or Bahia and Lencois. Or Manaus and the Amazon. Or Olinda/Recife and Fernando de Noronha.
Want to visit Brazil during carnaval? Consider going north to either Salvador de Bahia or Olinda. The further north you go, the more you actually ‘participate’ in the festivities.
Go SAMBA!