在撰写考研英语作文中的建议信时，你可以遵循以下结构和步骤：
写作结构
自我介绍和写信目的
开头要自我介绍，并说明写信的目的。
提出建议
委婉地提出你的建议和改进措施。
期盼回复
表达希望对方采纳建议，并表示感谢或期盼回复。
写作素材
常用词汇
feedback（反馈）
feasible（可行的）
suggestion（建议）
proposal（提议）
venture（冒昧做某事）
beneficial（有益的）
advise（建议）
suggest（建议）
recommend（推荐，劝告）
wise（明智的）
常用表达句
首段
You have consulted me for some advice about how to improve..., so I will try to make some constructive 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...
中间段
I’d like to suggest that...
May I suggest that...
Why don’t we...
ln my opinion...
I feel that it would be beneficial if...
示例段落
```
You have asked me for some advice on how to improve your English study. I will try to give some useful suggestions. I am writing to you to present what I think on the further improvement of your English study so as to help you achieve better results. I would like to make a recommendation that you should practice reading English every day and try to imitate the pronunciation of native speakers.
May I suggest that you could watch English movies or listen to English songs to improve your listening skills. Why don’t we also discuss some specific topics in English to practice your speaking and writing abilities？ I feel that it would be beneficial if you could keep a vocabulary journal to record new words and phrases you encounter.
Thank you for your attention. Please take good consideration of my advice. I trust you will take my suggestion into account. I hope that my suggestions are helpful for your decision-making anyway.
```
以上是撰写考研英语作文中建议信的基本结构和素材，你可以根据自己的实际情况进行调整和补充。希望这些信息对你有所帮助，