Don't try to emulate popular streamers. Think about what type of streamer you want to be and what makes you different
Make sure you iron out any technical problems, such as lags and frame drops, or bad audio. You don't want to be known for technical difficulties
Be sure to pick a sleek design and nice overlays that don't take away from your gameplay, but also align with the message that you want to send
Pick 2-3 colors that align with your brand. Use them on your Twitch channel, in your graphics, and across your social media platforms