Tibetan has some differences from mainline Brahmi-derived scripts. For consonant clusters, Tibetan doesn’t use a vowel-killing virama as much as other Brahmi-derived scripts. Instead, they frequently place small versions of the “extra” consonant above or below the parent syllable. Predictably, the stacked characters frequently (usually?) turn into a ligature (i.e. what looks like a single character and sometimes abstracted slightly). For example, the syllable glyph adorning has in the centre a “ka” glyph, with a “oo” diacritic on the top and a “r” on the bottom, making “kroo”. Note: this stacking is done even more when used to write Sanskrit than native Tibetan.
For punctuation, Tibetan uses a dot (a “tsheg”), placed relatively high up (around where the dot of an i lies) to separate syllables. The single dot might have derived from a “double tsheg“, shaped like a colon. Note that this has the effect of marking when the implied vowel should be retained, and when the vowel should be dropped and the character should represent only the consonant.
Tibetan also use a short vertical stroke (a “shad”) that looks like a very skinny cuneiform wedge, that functions similarly to the Latin comma and/or the word-continuation hyphen. While Tibetan uses a space after shads, they do not have a word separator. There are also several characters used to denote the beginnings of passages, verses, chapters, and (in some instances) pages.
There are two versions of the script, one with a horizontal line at the top (the “head” line), which is mostly used in printing, and one without, used mostly in handwriting. If you hear someone talking about headless Tibetan, they are probably talking about the latter script and not decapitated corpses.
Tibetan is an extremely conservative orthography. They still spell things the way they were spelled in about 900 AD, despite the spoken language having moved on. (To make an English-language analogy, it would be if we used Late Old English spelling now. While it would mean that we could read Beowulf in the original, it would make it even harder to learn to read!)