There are several types of ads that you can run on TikTok to maximize conversions and achieve the best return on ad spend (ROAS):

1. In-feed ads: These ads appear in users’ main feeds, and they look similar to organic posts. They can be in the form of video, photo or carousel ad.
2. Brand takeovers: These ads are the first ad that users see when they open the app. They can be in the form of a video or a photo, and they typically last for 3-5 seconds.
3. Hashtag challenge ads: These ads allow brands to create branded hashtag challenges that users can participate in. They are highly engaging and can drive a lot of user-generated content.
4. Branded lens: These ads are interactive and allow users to try on virtual products, such as makeup or clothing, or put virtual stickers on their videos.
5. Influencer marketing: Partnering with popular TikTok creators to promote your products or services can be an effective way to reach a large audience and increase conversions.
6. Dynamic Product Ads: These ads allows you to show product ads to users who have recently visited your website, or viewed your product catalog.

It’s important to note that the best type of ad will depend on your specific goals, products or services and target audience. A/B testing different ad formats and targeting options can help you identify which type of ad works best for your business.