Portrait-0044.png
A front-facing portrait is arguably the hardest pose to get right. The face's symmetry is unforgiving, and even a slight deviation from correct proportions is immediately noticeable.
The real gotcha here is the fact that there's no perfect front-facing reference. The head is never perfectly aligned with the camera, and the slightest tilt or turn can throw off your measurements.
Honestly? You won't be drawing this angle that often — unless, well, you're grinding through a 1000-portrait project like I am.
By all means, go for 3/4 or profile views instead.
Portrait-0044-ref.png
Portrait-0044-ref-with-loomis.png