There's no simple trick to knowing the gender of every single French noun (other than looking in a dictionary), but there are several categories of words that are always or usually masculine.
The French words mauvais and mal can be tricky for French students because they both belong to three different parts of speech and have similar meanings. If you have a poor understanding of the difference, it wouldn't be a bad idea to read this lesson.
The French words meilleur and mieux can be tricky for French students because they are the comparative/superlative forms of the oft-confused words bon and bien, respectively. This lesson is your best bet for gaining a better understanding of this confusing pair.
Multiplicative numbers are, unsurprisingly, words used to multiply nouns. The numbers themselves can be adjectives or nouns - either way, their gender agrees with the nouns they modify / replace.
Adjectives comprise one of the eight French parts of speech, but certain members of other grammatical categories can sometimes be used as adjectives. These "non-adjectives" are invariable: there's no gender/number agreement with the nouns they modify.
Most French nouns and adjectives become feminine with the addition of -e, but there are some exceptions. Some nouns require an additional spelling change, depending on the final letter(s) of the word.
While most nouns, in both French and English, can be singular or plural, some can only be one or the other - and dozens of these don't "match up" in the two languages. The nouns on this page are plural in French but singular in English.
Generally speaking, articles are much more common in French than in English, but there are exceptions, such as when certain prepositions are followed by nouns.
When used as a noun or adjective, the present participle follows the same agreement rules as other nouns and adjectives, and some verbs have a different present participle conjugation for these usages.
While most nouns, in both French and English, can be singular or plural, some can only be one or the other - and dozens of these don't "match up" in the two languages. The nouns on this page are singular in French but plural in English.