What tools do people recommend for determining appropriate asset allocation? I'm 30 years old, still have a long time to build up a stache and want to be as aggressive as possible, but not stupid. I'm always second guessing how much % I should be allocating to different assets (like, if small caps historically get better returns over the long run and I'm willing to put up with their volatility, why not weight myself heavier in those assets?). Right now I more or less follow Personal Capital's recommendations, though I'm heavier on international stocks than what they recommend (I'm 30% developed, 10% emerging whereas they recommend ~26% international), which puts me about 1% of historical risk to the right of their efficient frontier. But yeah, I have a hard time really deciding on an asset allocation and not second-guessing myself (though I do avoid actually constantly tinkering). So what tools do people recommend for determining your asset allocation?