You want a bunch of uncorrelated asset classes, globally diversified (that bear risk premia) and maybe some commodities.
Usually, the more balanced the weights are between the asset classes, the smaller the overall volatility of the portfolio - the smoother the returns are.
For a quick comparison of different portfolios, check out PortfolioCharts' visualization:
Typically rebalances monthly.
PortfolioCharts - choose, create, backtest static portfolios
PortfolioVisualizer - backtest portfolios