1. Express gratitude for all those times you got her incredible hand-me-downs.
She outgrew her [insert fancy designer] purse you’ve been eyeing for years? You’re the first one to get it. If you’re lucky, you get to borrow her mile-high stilettos that would go perfect with that new Nordstrom dress you just got. Having her hand-me-downs significantly improves your wardrobe options, and thus you are better-accessorized or better-dressed because of her.
2. Thank her for those times she shuttled you from place to place once she got her driver’s license.
Those were exciting times, when the two of you could just pick up and leave together to hit the local mall, with no parental supervision. If you grew up in a single-parent household like me, your older sister served as more than just a sibling, but as a surrogate mom. Thank her for the times she picked you up from your friend’s house, or drove you to Chili’s to eat after a basketball game, or randomly took you on a joyride through town just to get out of the house.
3. Be thankful for the years of wisdom and experience she has under her belt to share with you.
Whether it be job-related, makeup-related, or guy-related, your older sister is always there to give you advice when she’s “been there, done that.” I distinctly remember my older sister endlessly coaching me on mock interviews before my law school interviewing season, helping me secure job offers that I don’t know I would have gotten had I not had her help. She’d also give me some tough love on my work wardrobe choices (always urging to go with the more conservative choice), and though I would resist at times just for the sake of rebelling, I knew she was right in the end.
4. Show appreciation for the moments that she made it a priority to drop everything to cheer you up.
The time you broke up with your Match.com beau of barely 3 months, and were down in the dumps? Sister was there to pick up the pieces and take you out for a fun night of shots and dancing. The time you sensed a hostile work environment? Sister was the first to hiss at your bosses and help you navigate out of the mess. She knows you because she IS you — and getting you back to fighting form is her priority over anything else.
5. Relish in how different you are from each other.
Though there will inevitably be times that you drive each other crazy because there are things you don’t “get” about the other sibling, understand that these differences are what make your sisterhood so special. One sister might be great at generosity; the other might be better at organizing get-togethers. You might bicker from time to time, but at the end of the day, recognize that your unique personality traits bring different things to the table and help balance each other out.
6. Thank her for “breaking in” your parents.
You know the reason why your mom was so much cooler about you attending sleepovers or spending a more reasonable amount on back-to-school clothes shopping was because your sister broke them in. Whereas every sleepover your sister wanted to attend had to be presented as an official case to your parents, you being next in line would only have to say “Mom, I’m headed to Nataly’s for a sleepover” and get a simple “sure.” Also, the jeans that cost over $50 were never an issue on your next back-to-school shopping expedition, as your sister paved the way of making them understand that this was a realistic price range for jeans among junior high-ers.
7. Thank her also for setting the bar high.
Going along with paving the way, thank your sister for setting the bar high in terms of academic achievement and otherwise. My sister, the more naturally intelligent of us two, was an infuriating figure to grow up with. Whereas I couldn’t break into the 1500 with the SAT, she would seemingly effortlessly score in the 99.99% percentile of every standardized test she took. She got into great, top schools — which only propelled me to work harder to keep up with her. I think it was a healthy sense of competition, and though there were times I couldn’t keep up, I at least had a bar of some sort I wanted to meet. Also, seeing your sister in a healthy, committed relationship makes you recognize you want to similarly set the bar at that level of intimacy, care, and concern. You can count on your sister being an aspirational figure, and you are grateful to have such kick-ass female role model in life (apart from your mother).
8. Be happy when she’s happy.
When your sister finally seems to meet “the One,” or receives an amazing promotion at work, you are genuinely thrilled. No sibling rivalry or jealousy… just a sense of joy knowing that she deserves every ounce of happiness through her newfound source of fulfillment. You’ve seen her through the years deal with craptastic dudes and work colleagues, so when you see her reach her pinnacle of contentment, you yourself are content. 
