Variety is the spice of expanding your roleplay. Players and GMs, try new races, classes and playing the opposite sex if you haven’t before. It will expand your Roleplaying experience and add to your skills. GMs,including a variety of NPCs for the players to interact with of different races and classes will make a location more exotic.
i often use different accents, voice tones, expanded masculinity or femininity in my voice to help distinguish each NPC and monster as unique. The players enjoy it, laugh and try it with their characters as well.
Its variety in roleplay that can keep a game system fresh.