第一部分：说明写信目的

You have asked me for some advice on how to improve … . I will try to give some useful suggestions .

I am writing to you to present what I think on the further improvement of … so as to …

I would like to make a recommendation that …

I am writing to advise you of …

第二部分：提出建议

I'd like to suggest that …

May I suggest that …

Could you please …

Why don't we …

In my opinion …

I feel that it would be beneficial if …

第三部分：期盼回复

Thank you for your attention .

Please take good consideration of my advice . Thanks .

I trust you will take my suggestion into account .

I hope that my suggestions are helpful for your decision-making anyway .

I hope you will find these suggestions / proposals / recommendations （建议） helpful / practical / useful （有帮助的，实用的） .