第一部分：說明寫信目的

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：提出建議

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：期盼回復

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(建議) helpful/ practical/ useful(有幫助的，實用的).