' 많은 성원 바랍니다.' or '많은 지원 바랍니다.' 라고 씁니다. in some campaign, event, fundraising campaign and so on. '제발 도와주세요. please help us' could be seen too pitiful depends on the situation, so it should be used a bit carefully. '부탁드립니다.' is a bit different, it's similar to 'please'

부탁드립니다.

제발 도와주세요. similar to 'please help us' as you know. meaning can be slightly different depending on context or situation.