700 events are not enough for Lookalike. It is recommended to have a minimum of 1000 conversions.
In your case I would suggest you running a video ad. When you have enough views, create a lookalike of 95% Video Views. It takes not a lot of time to achieve but the results are usually good. And generally, video ads perform better than images. After that, you can create other lookalikes as Website Visitors and etc.