首先(shǒu xiān) - first of all, first and foremost in Mandarin

首shǒu先xiān，感gǎn谢xiè大dà家jiā来lái参cān加jiā。

First of all, thank you all for coming.

我wǒ们men首shǒu先xiān需xū要yào制zhì定dìng计jì划huà。

First and foremost, we need to make a plan.

首shǒu先xiān，你nǐ需xū要yào理lǐ解jiě问wèn题tí。

First, you need to understand the problem.

首shǒu先xiān，我wǒ们men要yào洗xǐ手shǒu。

First, we need to wash our hands.

首shǒu先xiān要yào保bǎo持chí冷lěng静jìng。

Above all, you must stay calm.