It's really tricky to know if you're not a fluent speaker. If the word has an indefinite article, it's easy to know (ei - feminine, en - masculine, et - neuter). In Norwegian we don't have "the", so instead we add to the ending of the word, but this is only in singular form (-a is feminine, -en is masculine, -et is neuter). Figuring out what gender the noun is, without any of the hints above, can be very difficult. I suggest you try to say it out loud with the different endings and see what sounds best, this is what native Norwegians do when in doubt. It isn't actually necessary to use feminine. It's becoming more and more common to only use masculine and neuter, so common that our teachers allow it. In that case, all feminine words are masculine, so you only have to distinguish between masculine and neuter. Good luck!

Adding to Karoline's answer: Whenever you're learning a new noun, it's always a good idea to learn the article of the noun along with the noun itself; that way you'll internalize its gender more quickly. So, for example, if you were to learn the Norwegian word for "house", you'd memorise this as "et hus" - and thus remembering that this is indeed a neuter noun. You can look up any Norwegian noun to find its gender and inflection pattern in this free online dictionary: http://www.nob-ordbok.uio.no/perl/ordbok.cgi?OPP=&bokmaal=+&ordbok=bokmaal (Just make sure you're searching in "Bokmålsordboka" - and not in "Nynorskordboka") Right next to whichever noun you have looked up, you'll see a code indicating its gender and inflection pattern (in blue). Click on this blue code, and the inflection table will be displayed. As an example, when looking up the word "hus", you'll see the code "n1" in blue right next to it. When clicking on this, the table displayed will show you that this noun has the following two equally accepted inflection patterns: Et hus - huset - hus - husa Et hus - huset - hus - husene Have fun :)