Help getting baby to sleep?

I am having trouble getting my 7 month old daughter to sleep, she wont sleep in her cot in her own room she will only fall asleep in my arms and when I try to put her in her cot she wakes up immediately. If I put her down awake she cries hysterically as soon as I leave the room it is very distressing. She wont go to sleep on her own or without a pacifier and if I stay with her in her room she thinks its a game and tries to get my attention by laughing and crawling around the cot. She wont sleep much at all during the day I know I have to start a routine but it seems so daunting any advice?