My approach is simple: invest the vast majority of all money after expenses into VOO (S&P 500 index fund). First max out tax advantage accounts like 401k and IRAs, then regular accounts.

I have $1,100,000 in VOO. Trailing inflation adjusted returns are 7% ish. Call it $25,666 for the first 4 months of 2016. I KNOW market returns aren't smooth like this but it is a simple approach that works for me (I'm not selling this stock any time soon so ACTUAL returns thus far in 2016 don't matter to me at all).

The math to get to that number is (($1,100,000 x .07) / 12) * 4 months