* Alphabet: The Irish alphabet includes the following letters: a, b, c, d, e, f, g, h, i, l, m, n, o, p, r, s, t, u. Note the absence of j, k, q, v, w, x, y, and z (although these *can* appear in loanwords).
* Pronunciation: Irish pronunciation is quite different from English. Many letters have multiple pronunciations depending on their position in the word and the surrounding letters. For example, the letter "c" can be pronounced like "k" or "ch" (as in "loch"). The letter "g" can be pronounced as a hard "g" or a soft "g" (like in "gem"). Vowels often have different sounds than in English, too.
* Fada (á, é, í, ó, ú): The fada (a long mark above a vowel) is crucial. It changes the vowel's sound and length, significantly altering the meaning of a word. For example, "cailín" (girl) differs from "cailin" (which might not even be a word or would have a different meaning).
* Lenition: This is a softening of consonants, often indicated by a change in the spelling of the preceding consonant. This can be represented by an "h" following the consonant, or by a change in the sound of the consonant itself. It's a key aspect of Irish grammar and affects spelling.
* Grammar: Word order and grammatical rules affect spelling indirectly because they dictate which form of a word (masculine, feminine, etc.) is needed, which could alter its spelling.
* Learning Resources: The best way to learn how to spell in Irish Gaelic is through dedicated study. Resources like textbooks, online courses (like Duolingo or Memrise), dictionaries (both online and physical), and immersion are highly recommended.
In short, there's no simple formula. You need to learn the sounds of the letters in various contexts, the rules of lenition, the use of the fada, and the grammatical rules to accurately spell in Irish Gaelic. It’s a process of learning and practice.