Does anyone have some good tricks to memorizing all the accent marks and when to use them? I've just started and I'm having trouble with them.
It's tricky. I'm still pretty unclear on when to use ´ (acento agudo) and ˆ (acento circunflexo). The other ones are a bit more straightforward.
ç (cedilha) is a C pronounced like an S. Think of the English rule: C before E, I, or Y is pronounce S, like in "recent", but before A, O, or U it's K, like "car". It's the same in Portuguese; "recente" vs. "carro". When we conjugate a regular verb like "vencer", to win, in the first person present, we change the C to a ç, to make "eu venço", so that the S sound doesn't change. ç also shows up in words like "maçã", "apple", just to be annoying.
ã and õ (til) are nasal vowels, with a very distinctive sound once you're used to them. Listen to the difference here: http://translate.google.com/#pt/en/ra%20r%C3%A3 You'll see a lot of words ending in -ção, some of which are cognates of (related to) English words that end in -tion, like "ação", "action".
à (acento grave) is used in contractions involving the preposition "a", meaning "to". For instance "a" + the definite article "a" = "à", "to the". It doesn't affect pronunciation.
I know a lot of one-syllable words like "lá" ("there") or "vê" ("he/she sees") have accents, but not all of them...and of course "você" with a circumflex is an important one to remember. Hopefully someone else can explain the rest, or correct anything I got wrong.
Edit: I said there were only 2 uses for à. There are actually a bunch. I should really be asleep right now.
Edit2: Davu posted these great links: http://www.learn-portuguese-with-rafa.com/brazilian-portuguese-pronunciation.html and http://www.learningportuguese.co.uk/language/diacritics.html The first one has some great stuff about acute and circumflex accents...they make a bit more sense now.
Edit3: Also from Davu, this discussion, a while back: http://www.duolingo.com/comment/525311
The website shown is a good start to understand stressed syllabes. But beware: the "grave" accent does NOT stress syllabes. (Àquele remains stressed in the second last syllabe).
The tilds "~" are well explained above (they DO stress syllabes, except when there is another accent in the same word)
And the "grave - à" is used only when a preposition "a" is merged with an article "a", or with a word beginning in "a". (It does NOT stress syllabes)
The other two "agudo" and "circunflexo" are the main ones. They are used not to change soundind, they are used to stress syllabes whenever a word is stressed in a syllabe that is not the one told by standard rules. (See website for rules).
Please notice that even if they are not used with the objective to change the sound of the vowels, they DO that by consequence.
Here goes their soundings:
The "agudo" accent makes an "open" sound, while the "circumflexo" makes a closed sound. See:
Á - sounds like the beginning of the "i" in "fight", similar to a in "car".
Â - sounds like the u in "pub"
É - sounds like the e in "bell"
Ê - sounds like the a in "may"
Í - has no changes
Î - doesn't exist
Ó - sounds like "lock" - go american pronunciation here
Ô - sounds like "go"
Ú - has no changes
Û - doesn't exist.
Vowels with no accents can change between these two forms, it depends on the word (open and closed).