Think about why you want to write songs. Do you have things that you want to say?.   Do you want to write for self satisfaction or to have music published? If you are writing for personal expression you can make your own rules. If you want music published you may be good enough to get publishers to accept your style, but most likely you will need to play by the publisher's rules. Listen to songs and figure what makes a good song. The more enduring writers may not have studied song writing but they listened to music and it became a part of them.