[R-sig-finance] PTF Optimization Beyond Historical Data

[L.Isella]

Dear All,
I am doing some portfolio optimization for a small financial company.
As a first step, I just solve Markowitz model based on historical data.
Now, the company trades above all European ETFs and  Japan equities.
We need to improve the historical returns and correlations of the assets for a portfolio made up of about 18 assets.
Since I am a bit drowning in the vast literature (time series, technical analysis, CAPM and so on), I would like to know if anyone can come forward with a bit of advice.
In order to start, the simpler the better. Finally, is there some sort of routine or standard method which is taken as a "benchmark" for the composition of the efficient portfolio?
If yes, is it implemented in R?
Lorenzo