Words with suffixes –ung, -heit, -keit, -schaft, -tät, -tion - always feminine Words with suffixes -ling, -ist, -ant, -ismus - always masculine Words with suffixes -chen, -lein - always neutral You can remember this, it makes learning easier

You have to write those down keep writing remebering again and again until you finally keep those by heart. It's not that serious when you made mistakes when you talk to some native speakers, but if it comes to academic essay, things gonna be really tough, cause people from Germany,especially professors, they do judge. Even students who work at the college don't give a shit to the emails which content lots of grammer mistakes. If you are only for travelling, getting know people, maybe several mistakes are not big deals, but if you really want to do something with Germany, like studying some specific majors in Germany, which there are no english courses offered, grammer mistakes are really gonna be fatal..

For the words that do not fit those patterns, try making a mental picture with something that reminds you of the gender. Like an alien in water (das Wasser), picture of a guy on a skirt (der Rock), or a woman sitting on a clock (die Uhr).

Well, I guess the best way to do this is to speak with german natives and/or read german Books/Newspapers/Articles/Texts. Hope that helps.

There is no easy way. For instance the word for a girls skirt in German is masculine. Why would woman's clothing be masculine? And it does no good to ask a German because they dont know.