Understanding a JLPT practise question with ものなら


This sentence comes from a question in my JLPT practise book that is part of
an explanation of the use of `ものなら`:

>
> 一度{いちど}仕事{しごと}を手伝{てつだ}おうものなら、それをいいことにあの人{ひと}は何度{なんど}でも頼{たの}んでくるから、気{き}をつけたほうがいい。

My fractured translation is, "If helping out a little is something you intend
/ that's something good / asking that person's help / you should take care."

As you can see, though, I can't make the connection between asking for help
and why one should take care.

What exactly is this sentence saying, and how does it relate to the use of
`ものなら`?




From JGram: ～う／ようものなら： もし～ようなことをしたら．．．（大変なことになる） Once if (one) happen to ... ,
then (bad consequence)."

So the first part of the sentence does not imply the listener is the subject,
but the 'that person' in the next part of the sentence instead.

So basically it is saying: "You should be careful because if you help that guy
out once, he will take advantage of that (act) and ask for favors very often."




From JGram: ～う／ようものなら： もし～ようなことをしたら．．．（大変なことになる） Once if (one) happen to ... ,
then (bad consequence)."

So the first part of the sentence does not imply the listener is the subject,
but the 'that person' in the next part of the sentence instead.

So basically it is saying: "You should be careful because if you help that guy
out once, he will take advantage of that (act) and ask for favors very often."

