Pictured: Waltz of the Wildflowers dress Tips for Styling Your Modest Spring Dress: Layer Up: A light cardigan, denim jacket, or blazer can add warmth and style on cooler spring days
As you point out, I would also avoid showing the undershirt when wearing formal or semi-formal clothing
Three-quarter sleeves provide coverage while maintaining a polished look
Consider cream, champagne, blush, or even patterned dresses with floral details
Just like your capsule wardrobe of clothes, invest in the best quality you can afford and think about including trainers, a court shoe, a boot (either ankle or knee high) and some sort of flat
Additionally, Title Nine's A-line, wrap dresses, and racerback styles are almost too versatile, and good to go no matter what you're up to