Step 1. Ask her to set aside her identity
Make clear to your beloved bridesmaid that your future home's photo wall has no place for her like...*gestures wildly* ...this. Also explain why having your wedding published on a traditional wedding style blog matters more to you than she does. You need your wedding to be validated by strangers all over the internet who are planning their own weddings with blush roses and spanish moss and clever directional signage. She might look bewildered at this point, but just push through. Your wedding isn't about love and acceptance; it's about curated content creation. Obvs.
Step 2: Agree to pay for the professional services you're requesting
Covering her tattoos
Offer to pay for specialty makeup application. This may require special consideration in hiring makeup artists for your big day, but I'm sure that you won't mind spending the time researching wedding makeup professionals with this impressive skill set, and paying them accordingly. Being a considerate bride, of course you'll accommodate your bridesmaid's needs during the extra hours she'll gladly dedicate to spending in a chair on your wedding day, rather than waking at a sane hour.
Getting rid of that distracting vivid haircolor
There's no such thing as a simple color correction, but you're happy to pay any price to avoid fire engine red hair in your photos. Simply make an appointment with the most highly reviewed colorist in town, because you obviously can't trust your bridesmaid to handle this herself. Also set aside cash to compensate your bridesmaid herself for the opportunity cost of her time all day in a chair at the salon. I hope your bridesmaid isn't a lawyer. Or physician. Eek! That could get expensive for you, valuing the time of your loved ones.
That's me, there, with the purple. Did you even notice me? I bet you looked at the bride first.
Sarcasm aside, please take away these points:
1. You will be a bride so marvelously beautiful that NOTHING near you could possibly take away from that. Stop the cruel self-talk about there being a scarcity of attention for you and your spouse. You are loved.
2. Our outward appearance is our identity. Asking anyone to specifically change any part of themselves to conform to your personal beauty standards is...well...it's a lot of adjectives that I won't say because of the Thumper principle. Love your bridesmaid for the diverse flavor she brings to your life, for the memories you've built together, for the woman she is. If that isn't enough for you, I challenge you to reflect upon why.
Let's empower the women in our lives to be their most authentic, fabulous selves. Let's celebrate them.
P.S. This topic seems to often coincide with brides also asking their closest posse to withhold family planning. Maybe one day I'll find the words to address that, but today is not that day.