Plurals are hard :(
I've read and understood the rules to predicting the plural, eg. 'Kvinna' '(a' becomes 'or') to 'Kvinnor'. And I have had quite a few successful runs of the plural tests. But is there a easier way to learn the process of predicting the plural change?... Like a memory game? I'm not looking for a shortcut per say, But I am having difficultes learning them.
It all depends on the ending of the word.
ends in -a: en kvinna-- kvinnor en flicka--flickor
other en words (most fall here): en pojke--pojkar en cykel--cyklar
international words/"loan words" (often the emphasis placed on the second half of the word, whereas swedish words usually emphasize the first syllable) en station--stationer en dator--datorer
vowel shifting (these you have to memorize, are the exception usually) follow the ending of int'l words en bok-- böcker en stad--städer
end in vowel-add -n ett äpple--äpplen
all other ett words ett hus-- hus ett barn--barn
en läkare (en words that end in -are, usually professions, do not change)--läkare
en tekniker (en words that end in -niker, usually professions, do not change)--tekniker
Your best bet is just practice practice practice. You can also try adding courses on memrise like this one for example: http://www.memrise.com/course/457080/duolingo-swedish-en-or-ett-plural-endings/
I admit I haven't used it as much as I would like to but so far it's been helpful to me. It's very good to use in conjunction with duolingo! Good luck!