There are semantic and phonological cues to recognizing nominal gender in Hindi. These are only reliable part of the time.It so happens that many Hindi words ending in `-ii', for example, 'billii', are feminine. Unfortunately, words from Sanskrit like 'tyaagii, ascete, renunciant' are usually maculine, so you have to know whether a word is truly Hindi in origin, or Sanskrit.
There are a few characteristic endings, not only -aa and ii, which point to masculine and feminine. There isn't so much to memorize, except when vocabulary of Sanskrit, Persian, and Arabic origin is concerned... then, sad to tell, there are lots of details. I am under the weather today, and cannot write much, but I will gladly send you the information I have. You can write to me, firstname.lastname@example.org
Oh yes, and you should get the Oxford Hindi-English dictionary (from Amazon); you will discover most of the regular gender traits right away on your own. Get in touch with me when you can.