Wearing something comfortable, practical and not too flashy is always my go-to for a day of firearms practice.
When I am going to the range, the top priority for my outfit is to 1) be comfortable and able for me to move in, and 2) Not be too revealing or inappropriate. I want other people at the range to see me and think, "She dresses the part so she must know what she's doing."
Do I normally care what other people think about me? No. Do I recommend that other people care about how others feel about them? Also, no. BUT the one, rare time I am self-conscious about my choice of clothing is the range. We've all seen the girls who show up to the range with their bodies on display more than their firearms skills. Yes, it is great that they love their body BUT the range is a very judgemental place for everyone, especially females- don't give anyone else extra ammo (no pun intended) to pass judgement upon you.
Keep in mind- I dress for the type of range day I am going to have. If I'm going to an actual training day that I'm attending, I will wear a pair of 5.11 cargos (preferably in a color that can hide dirt well because I'll probably end up shooting prone or kneeling at one point during the day), a long sleeve t-shirt, and a hat to shield my face. The sun can beat down on you during an outdoor range day and theres nothing worse than coming home sunburnt after the range.
If I'm going to the range with just my husband for some target practice I'm a little bit more stringent on my wardrobe. I have a pair of 5.11 range leggings (they've been discontinued but if you can find them on eBay or Poshmark they're the "raven range tight") and I LOVE them. They're leggings but made out of a very thick material (not sheer when you bend over) and the waistband is double the thickness with belt loops. The only way they could be more perfect would be if they had pockets. Those are my go-to with a long sleeve tee or sweatshirt. There are other brands that make carry-wear or active wear geared towards carrying a firearm and I've tried them and never have been a fan. All of them unfortunately have just been ridiculously overpriced, horrible quality, and the waistband is never strong or stiff enough to hold up my range belt and feel secure. I love the 5.11 leggings because the waistband is sturdy and stays in place. If you can track them down on the resale market, I *highly* recommend them.
I steer clear of v-necks, low rise pants, or anything that is going to over expose me. Keep in mind, you will be shooting from lots of different angles and positions so a shirt that feels "just a tiny bit revealing" standing straight up could potentially be WAY more revealing if you're leaning forward/shooting laying down/etc. Besides, if you've ever taken hot brass down your shirt you will realize REALLY quick that a high neck line is always a better choice 😂
All in all, yes- it's important to practice at the range wearing what you typically do BUT I wouldn't recommend it in a class setting. I've even seen classes have a dress code, which is geared more towards safety, but still-dress for the range and you will never have anyone judging you on your choice of fashion.