I am writing this to my manager.
I’ve found a new job, and I won’t start working there for two months.
I would like to ask you if you recommend to me studying specific things, so that when I start working I will already know them.
Is it correct to use “to” in this context?
Your instincts are correct; the preposition sounds a little awkward there. I would suggest one of these two alternatives:
Do you have any recommendations about specific things to study?
Are there any specific things that you would recommend for me to study?