Learn Turkish: Keşke o şirkette staj yapsaydım, pratik çok önemli. - I wish I had done an internship at that company, practice is very important.

It is built by adding the conditional suffix -sa to the verb root yap-, followed by the past tense suffix -dı (with a buffer -y- in between), and the first-person ending -m. This -saydı combination indicates an unfulfilled condition in the past, which translates perfectly to wishing you had done something.

Do I always need to use keşke with the -saydı ending?

Technically no, because the suffix combination -saydım on its own already carries the meaning of "If only I had done." However, placing keşke at the start of the sentence is extremely common to emphasize the regret, similar to adding "If only..." in English.

Just as a refresher, why is it şirkette instead of şirketde?

This is due to consonant harmony. Because the word şirket ends in the voiceless consonant t, the locative suffix -de (meaning "at" or "in") must harden its first letter to match it, becoming -te.

Is pratik used for both the noun "practice" and the verb "to practice"?