Riding jeans
Armored riding jeans are a practical first upgrade because they look normal, move easily, and can include abrasion-resistant materials plus knee and hip armor.
Textile and overpants
Textile riding pants or overpants can add weather protection, more coverage, and easier commuting options. They are especially useful if you ride in rain, cold, or mixed conditions.
Check fit on the bike
Knee armor should sit over your knees when seated, not just when standing. If the armor rides too high or swings to the side, try another size or style.
Hip armor is worth having. Many riders focus on knees and forget that hips often take hard impacts.