Lululemon is amazing and a lot of girls love that brand! Their workout leggings are so well made and they make the butt look so good but that brand is quite expensive (try going to a Lululemon's outlet) I really like workout gear from nike too! The workout tops/bras/yoga pants from Victoria Secret are also awesome! (: I think a really good workout outfit combo is: Bright colored workout bra with a loose flowy tank on top and then workout leggings/ shorts (: Hope this helps!
I don't see the point in things like lulu lemon, seriously $100 for yoga pants. Most of ten don't even workout in them it's ridiculous. And Victoria's Secret pink has workout stuff but it's like $40 for fucking leggings. I workout almost everyday and I et my workout clothes from h&m, old navy, forever21, and target and all of them hold themselves together pretty damn well. With those others your mainly paying for brand. The nike sports bras with the spaghetti straps have exactly the same as the ones at target it just has a swoosh so it $65 instead of $12
I like wearing Under Armour if I'm doing more cardio. For yoga Lorna Jane has some cute sports bras, and yoga crop pants I just get at Target or Gap lol. Michi has some sexy stuff, and Sweaty Betty is really nice but both are pricey!
try sweat wicking material, tight around bust for support, synthetic stretchy material pants or shorts. Lulu lemon is good brand but expensive. However if u shop around u can find really good stuff at places like Walmart target and department stores. Stay away from the colour white because it's stains and often transparent with sweat. take a look around to find styles she'd like is ur best bet