I know what they do and I know why they are there but rarely remember the correct names of those dots, lines and squiggles above and below letters to amend pronunciation. Perhaps it would help if I understood the etymologies and thus knew why they were named.
Acute accent - not 'accent' in the sense of 'mode of pronunciation used', normally due to point of origin, but the written instruction. The term 'accent' came to English from Middle French, where accenter, meaning 'stress' or 'accentuate' and used as a verb, came from the noun. This in turn is derived from Latin accentus, with the same meaning, and ultimately from Latin ad 'to' and cantus 'a singing' and has exactly the same origins as the word 'chant'. The addition of 'acute', to differentiate from the grave accent (see below) and to show indicate a higher pitch than the latter, comes to English through the same French and Latin route and is ultimately from Proto-Indo-European ak meaning 'to a point, sharp' - and is why the term is used to describe such as an illness or feeling. It came to French from the use of the apex in Latin, itself indicating a long vowel sound.
Breve - indicating a short vowel is much easier to see as this comes from the Latin brevis meaning 'short, brief'. It is the opposite of the macron (see below)
Cedilla - comes from the Spanish where, along with French and Portuguese, it is used to instruct the speaker to use, for example, the sibillant 's' (as in the English 'facade') instead of the hard constant sound for 'k' (as in the English 'arcade') when under the letter 'C'. This is the most common example although, in truth, the use is much more complex. The image of the cedilla comes from the Visigoth representation of their letter 'Z', easy to see in the image.
Circumflex - used to mark vowels where pronunciation begins at a high pitch then falls, this comes from Latin circumflexus or 'bent around', a reasonable description of the symbol.
Diaresis - comes from the Greek meaning 'division, separation, distinction', it is used to show where a vowel letter is not pronounced as one vowel when alongside another vowel. In English these are always loanwords, best seen in names such as Zoe and Cloe, although today the use of the symbol is rarely seen.
Grave accent - shares the same 'stress' origins with 'acute accent' above, the addition not only to differentiate but to indicate a lower pitch than the acute accent. This French term shows it comes from the Latin gravis which, when used in the sense of sounds, is used as 'deep, low, bass' and ultimately from the Proto-Indo-European root gwere or 'heavy'. This ancient root has produced words of similar meaning in Greek and Sanskrit as well as Latin gravis which also gave terms meaning 'ponderous, burdensome, loaded, oppressive, grievous, troublesome' and also 'pregnant'.
Hacek - most often seen in Baltic, Slavic and Finnic language is also known as a 'caron'. Such changes the pronunciation so the vowel sound begins low and then rises, ostensibly the reverse of the circumflex (see above).
Macron - is used to indicate a short vowel and is the opposite of the breve (see above) and is derived from the Greek makron literally meaning 'long' and most often seen in the suffix 'macro-'
Tilde - is a stroke over a word to indicate missing letters. It is related, not in its use, to the 'tittle' that dot above the ninth and tenth letters of the alphabet. The 'tilde' and 'tittle' share an origin in the Latin titulus meaning 'inscription, heading' - this meaning also seen in the origins of the word 'title' and for obvious reasons.
Trema - is simply another name for the diaresis (above) or umlaut (below). The different name is used because it comes from the Greek trema meaning 'perforation, pip, orifice' and thus a description of the symbol rather than the function.
Umlaut - another name for the diaresis or trema (above), this coming from the German ambi 'about' and laut 'sound'. The term was first coined as recently as 1774 by poet Friedrich Gottlieb Klopstock but not used in the sense 'modification of vowels' until Jakob Grimm did so in 1819. Earlier uses of the umlaut had the same function but were not known as such but simply accepted as the norm. Klopstock used the German hlut which shares its origins with the modern English word 'listen'.
Did learning the origins help? Not in the least. But it did confirm that 'umlaut' is among the most wonderful-sounding words in any language - ironic considering its literal meaning.