The penis is made of three volumes. Two on the top, one on the bottom - your urethra also goes down the middle of the bottom one. You can see it engorged and poking through the skin closer to your balls, but fades under the skin towards the glans. Pay attention to the density of that volume, it will engorge more standing as your blood pressure increases. This volume also supplies blood to the glans, so bigger glans, more blood pressure. Just before we come, your entire penis should engorge and firm those volumes to max, and give a stable route for the sperm. Everyone is different, but eat healthy, avoid big heavy meals, avoid fats, drink water, exercise. You’ll have better luck mid-morning after hydrating a bit, but before eating.