Trouble with unwanted hardline edges (overlaps)
You may sometimes hear Anna talk about 'hardline edges'.
This is the term Anna uses for the marks that can appear on the paper when brushstrokes overlap and create darker marks.
It happens because the paint is transparent, so in the places where brushstrokes touch or overlap, there's more pigment on the paper and it looks darker.
Most of the time, hardline edges work to your advantage when you're painting realistic subjects - even if you didn't mean for them to happen. Very few things in nature are completely flat or smooth, so these marks can help to build up the appearance of texture (which Anna refers to as 'visual texture').
If you make sure that you apply the paint in the direction of form (Anna always shows you how to do this in each tutorial) then the overlaps can actually work to help create your subject's form.
Most of the time, Anna seeks to create these overlaps by using a stippling brush technique. See the Brush Techniques Knowledge Base video for more information on this and demos.
If the marks are standing out too much to you, try not to worry. As the painting develops, you'll probably also continue to apply more layers of paint over the top of the one you're working on. With each new layer, the hardline edges will become less noticeable, without you needing to do anything to address them.