This is a strategic question and will depend on your strategy as well as your budget.
For beginners, we suggest building 1 Lookalike Audience and 1 Interest-based Audience.
However, there are a few tips to keep in mind. If your monthly advertising budget is less than $1,000 it is important to focus on fewer audiences, so you have enough results per ad set to allow the algorithms to optimize your campaigns.
The Lookalike Audience and Interest-based audience combination has several benefits.
It allows you to build a similar "Lookalike audience" from the people who showed interest in your store in the past, as well as discover new potential audiences that may be even more interested in your store based on their common interests.
By showing these two audiences the same ads, you are also able to see which audience is performing the best.