It is Crazy when you do not know Feminine from masculin
It gets better, promise. Learn new words with the indefinite articles, un and une as though they are a part of the word, as indeed they are. Memorize them together. You will save yourself a lot of headache later! With time it will feel more natural to use the correct gender with the words that you have reviewed over and over. They will become "glued" into your brain.
Lindakanga put together some great links and her advice is excellent.
Lastly, be patient with yourself. You will make mistakes- lots of them! Oh well! Laugh, learn, and move on.
I often make inferences on whether a French word is masculine or feminine based on certain hints. For example, a word will most likely be feminine if it ends in "ère", "elle", and sometimes "e" (but not always). A masculine word will sometimes end with "eur" or "eau". It's just one of those things in a language where it's hard to short-cut your way through it. I just try to remember all words that are feminine and masculine, and I understand your pain of forgetting the gender of a word.