Always swatch the blush or bronzer on the back of your hand, but first apply foundation then swatch them. Then you will get to know the true color.
When you are buying a bronzer, imagine your color after spending few days in sun (just imagine, don’t do it), it should suit you at that time as well.
You don’t need to try a lot of shades for a perfect bronzer. One darker shade or two darker shades from your skin tone will be the best.