Everybody should show your（应该是one's） true heart.
(It was that)(删去)people usually think more for myself(themself),and （think）（也可以删） less for （加the）others.This （might be）（换成更为肯定的is） bad for (people's)(删去) friendships（单数）.(Believe it or not,)（多余）my parents often tell me to think more for others,（一定要加and）treat everythings(不要s) by heart.
Sometimes,my family give（是gives） （some）（这里不要用概数词,删去） help for（应该是to） our neighbour(注意拼写,用复数).(加上everytime会好些)When our neighbours told(用say) "Thank(thank小写) you."to my parents ,I fell(换成always feel) very proud.I believe when my parents get older and older,they will get help from others,too.
（加上To show one' heart and help others is,否则没主语和动词）just like a key to the heart.I compare（用regard） people's hearts to（用as） a door（.And）（用逗号连接） （compare）（删去） the key to（用as） the way to treat people and help others.We infenty（这是啥词?） our keys,and we find our door.The key only to a door.
That seems to be friendly to everyone. （最后几句话表意不明……）