Shana tova umetuka

Despite the solemnity of the occasion, Rosh Hashanah is a festival, so it is an occasion for nice clothes, special meals and good spirits
"Out with the old year and its curses! In with the new year and its blessings!"
L'shana tova tikateiv v'teikhateim!
May you be inscribed and sealed for a good and sweet year of happiness and growth!

Chasidim like to bless each other not only for a good year - "Shana tova" - but also a sweet one - "Shana tova umetuka". The idea is that the good should not only be in G-d's eyes, but good from our perspective too - e.g. it tastes good.