Repetition! I believe the first ones are the hardest. Once you know the first ones you start to see patterns. Once you learn moon you see it in morning and you make associations. You realise that one moon cycle is a month. I'm horrible with remembering kanji so I had to use skritter when I started learning: http://www.skritter.com/ I think memrise is a good alternative but it's not the same as when you draw the characters. I also made sure to start with the easier kanji and make my way up to the harder kanji. A text book always starts with the easier kanji first and then build on that. I recommend following this process.