Kelly Letter Investment Recommendation

I'm getting ready to deposit (December 1st) a Fidelity account on December 1, as my wife is retiring from the post office and withdrawing from her TSP. I am still working, so we don't need the money. I have been with the Kelly Letter a long time, just seeing what people recommend doing with the deposit. Because of our jobs, we haven't been able to invest directly in a Fidelity account until now. The same is true with my retirement account as a school employee.