When thinking of what can define a person’s beauty, eyebrows may not be what most people consider. In truth, the shape of those arches can either highlight the beauty of your facial features or detract from them. Eyebrow shaping has been a part of the beauty routine across cultures for centuries and continues today to fluctuate in trends just like makeup and clothing.

The modern woman can now rock a full, magnificent, almost masculine brow with virtually no negative attention for it not being “feminine” enough. The brows of model Cara Delevingne and actress Lily Collins are prime examples of this straight, heavy, natural look that is only slightly trimmed. However, styles have vacillated over the years.

In the 1930s, women displayed thin, elongated brows matching the color of their hair.  Length was especially important, though brows were just an extended, gentle curve. In the ’50s, brows were shorter and looked natural, not just penciled on.  The arch was very slight, like that of Audrey Hepburn. The ’60s brow was similar to now — dark and heavy, though still well-groomed rather than bushy. They draw attention to the eyes by casting a curtain over them, making them gleam, and brows are flatter on the underside. Once the ’90s came, however, pencil-thin was in again.

Looking retrospectively, the current brow trend definitely appears striking, yet easy and comfortable to maintain. To achieve Delevingne’s dark and dangerous look that can also be classy and elegant, given the right makeup, be careful not to over-pluck.  You can always take more off, so start slowly — growing too-thin eyebrows back can be embarrassing and tedious. Focus on maintaining a clean middle between brows, instead of arching them underneath, and never pluck through the middle to make the brow less dense. Stick to their natural arch on top and use an eyebrow pencil to darken and thicken brows, covering up any spots where hair might not grow evenly.

Smaller and circular faces tend to need a bigger arch to contrast the minuteness of their face, while longer faces need much less of an arch. The smaller your face width, the shorter you will want your brow to be in length.

Check to see that your brows are not overcrowding the rest of your face. Looking at Brooke Shields or Jennifer Connelly, you can tell both women have large foreheads, giving more space for the hair to grow without it being too overpowering. If you have a smaller forehead, this may be a look you want to avoid.

If you are attempting to make a sleek, stylish arch, the lowest part of your brow that is closest to your nose should be at the same height as the ending of your brow closest to your ear. Stars like Angelina Jolie and Megan Fox benefit from their tall arches because it accentuates their strong cheekbones and jawlines.

For eye brow maintenance, pick up some castor oil to allow for naturally thicker growth, and do not forget to moisturize before bed.  Like the hair on your head, the less stressed you are and the more healthfully you eat, the better your brows will appear.

A version of this article ran in the Wednesday, Sept. 25 print edition. Christina Sahli is a contributing writer. Email her at [email protected].