Indented scars - is there any incision technique that can prevent this?

If a direct brow lift is done correctly, there should be no indentation of the scar. It is not only the incision which is the issue. It is what tissues were left underneath the inicision to support and bolster the incision line so that it does not contract inward and how the skin closure was performed. As the scar is quite narrow in this area, a re-excision of your scar with proper closure of the incision should correct your problem and enhance your brow position. Best wishes.

A photo would have been extremely helpful. However, generally speaking, before jumping into more surgeries that may translate into more complications, you might wish to explore subcision for elevating and smoothing the indentation. It is a relatively simple, relatively inexpensive technique that I have been performing since 1995, that has a several decades' long track record of safety and efficacy in all skin types. What's more, it typically engenders little to no significant downtime, and requires no surface cutting or stitches, so there is no concern about subsequent stretch scar development or stitch marks. You would be wise to make sure to consult with an experienced, board certified cosmetic dermatologist with experience in performing subcisions. Hope this helps and best of luck.