Fashion accessories for men and women during Italy's Renaissance varied from place to place and over time, but there are some general aspects that can be mentioned here. Of course, the wealthier a person was, the greater access that he or she would have to these accessories. Therefore, I will limit this explanation to the merchant class and the nobility.
Women would have worn a tight-fighting bodice and an ankle-length skirt or dress. Underneath this, she wore a very constricting corset, sometimes made of whalebone. Wealthy women would show off their fortune by displaying numerous pieces of elaborate jewelry made of precious metals and stones. Sometimes jewelry would incorporate actual gold coins in them. Married women would wear their hair up in long braids held in place with highly-crafted pins. Women might wear linen hats, hoods, or decorative hairnets. Sometimes they would further adorn these hats with exotic bird feathers. A type of platform sandal called pianelle was popular with women throughout the Renaissance. A lace ruff, also called an Elizabethan collar, became popular, especially in England, but it was often worn in Italy as well. This decorative collar was held in place by numerous tiny pins.
Men would often dress in puffy hose stockings rather than pants. Above the hose, a man would wear a simple codpiece (that sometimes doubled as a change-purse), which had been fashionable throughout the middle ages as well. Wealthy men would wear a tall hat to help distinguish them from peasants, who wore flat hats. Like women, rich men would wear jewelry to show off their wealth, but it was usually less elaborate. This might take the form of rings with a single gemstone, small loop earrings, and even gold or silver buttons. Decorative belt buckles were also popular. Interestingly, a small sword became a fashion piece for upper-class men. While occasionally used for dueling, a sword was more of a status symbol than a weapon.
Gloves of various materials, ranging from leather to silk, were worn by both men and women.