I am writing in reply to...
I would like to suggest that...
I am writing with my suggestions/proposals about...
I am writing to express my views concerning...
You have asked me for my advice with regard to ... and I will try to make some conductive suggestions.
You have asked me for some advice on how to improve... I will try to give some useful suggestions.
You asked for advice concerning( with regard to)... and I will try to make some suggestions.
I have received your letter saying...I recommend that...
I am writing to express my views about...
I hope that my suggestions are helpful for your decision-making anyway.
I would be more than happy to see improvement in this regard.
I believe that you will take my suggestions into serious account.
Please take good consideration of my advice. Thank you.
I would be ready to discuss this matter to further details.
Whatever you decide to do, good luck with your studies/work!