The trick lies in knowing for how long you will invest and whether you have determined the reason for the investment.
Now 10–15 p.c. is a very big gap but if you are implying that a 12 pc return is what you are looking for, then perhaps Indian equities are the best suited to answer your need. Why Indian equities you ask?? Well, when the economy is expected to grow at around 7–7.5 pc…and with the consumption pattern, populatoion, demograpy et al this is a pretty expected number and about 4–5 pc inflation, a nominal 12 pc growth is expected on equity investment. However, i believe that with an active fund management strategy 1–2 pc excess return over a decade to fifteen years is more than achievable. SO YOUR TARGET SHOULD BE QUITE OK.
CAVEAT:: If you do not know/understand equity, please do not do any fancy stuff, pick five mutual fund tops and do the investment through them.