I agree, not necessarily any logical rules, so you need to memorize the gender with the word. Consider this: French words (as well as many other languages) are made up of 2 parts: the word and the gender. If the gender is wrong, the whole word is wrong!! So be sure to learn the gender with the word. This makes a huge difference with some words, but in general, people will be nice about it if you say the wrong gender. To help you, make sure to frequently use new vocabulary to help you get a feel for it and if you become more comfortable with it through practice, you'll rely less on guessing!