Possessive adjectives describe the following noun, whether or not that is the subject of the sentence. That is really important to remember. Here are the meanings of the possessive adjectives:
MY
mon (if followed by a masculine noun)
ma (if followed by a feminine noun)
mes (if followed by a plural noun)
YOUR (informal)
ton (if followed by a masculine noun)
ta (if followed by a feminine noun)
tes (if followed by a plural noun)
HIS/HER
son (if followed by a masculine noun)
sa (if followed by a feminine noun)
ses (is followed by a plural noun)
OUR
notre (if followed by a singular noun - doesn't matter if masculine or feminine)
nos (if followed by a plural noun)
YOUR (formal)
votre (if followed by a singular noun - doesn't matter if masculine or feminine)
vos (if followed by a plural noun)
THEIR
leur (if followed by a singular noun - doesn't matter if masculine or feminine)
leurs (if followed by a plural noun)
Here are some tips for figuring out which possessive adjective to use:
If a word ends in -s or -x, it is most likely plural
If a word has an extra e at the end, it is most likely feminine
If a word ends in -que, -ée, -elle, or -tion, it is most likely feminine
If you have figured out that the noun is singular, but can't figure out if it is masculine or feminine, I would divert to masculine, since there are a lot more masculine words out there than feminine (but only do this as a last resort)
