Diet (high protein, high saturated fats, low carb), adequate quality sleep (enough hours, no interruptions, complete darkness), and compound exercises (a lot of guys like dead lifts for testosterone) are the first and most important steps to optimizing testosterone. There are natural supplements that are said to help, like boron, ashwaganda, and the previously mentioned pine pollen, but if those actually do anything, there's no point if the previous three areas aren't addressed.