Step one: stock up on a range of different fragrance oils (even if you adore florals and gourmands, be sure to pick up some citrus and spicy scents too) or invest in a kit that takes care of all that for you, like Fred Segal's The Blend ($150). We talked to Daniell DeMarne, Fred Segal's creative director and a woman who knows more than a thing or two about blending, and asked her to guide us to perfume-blended bliss. Once you've got your oils, DeMarne emphasizes that there's no wrong way to blend—if you don't like your concoction, simply try adding something else. She also says beginners should stick with what they know—start with scents you know you like (amber and vanilla are two of the most popular picks for women), and then experiment.
As a general rule, she says to start with the heaviest, headiest note, or whatever you want to anchor your scent (think amber, oud, sandalwood, floral). Then, layer on the lighter accents.