I tried starting with my parents. However, I discovered that most of my family through the third great grandparents had not been entered. If you already have constructed a tree, you could try the backward approach. For example, if you have any notables, they are likely to be on WikiTree already, then you can follow down that line as far as it leads to your family and enter the rest.
When I first started with the forward method I accidentally created duplicate profiles, and then I had to request merges.The backward method from an ancestor already on Wikitree prevents this.