I have looked at a lot of portfolios. The gap between the artists who get hired and the ones who do not is rarely raw skill. It is presentation and judgement.
1. Too many pieces
Twelve good assets is a worse portfolio than four excellent ones. A reviewer assumes your weakest piece is your true level. Cut until it hurts.
2. No wireframes, no texture sheets
Studios hire for a pipeline role. Show the low-poly, the UV layout, the texture set and the poly count. A beauty render alone tells them nothing about whether you can work inside a budget.
3. Lighting that hides the work
Dramatic rim-lit renders on a black background look great and communicate nothing. Include at least one neutral studio pass where the material reads honestly.
4. No context of scale
An asset floating in a void has no size. A simple reference cube, a character silhouette or a ground plane instantly tells the viewer what they are looking at.
5. Never finishing
The most common failure is a folder full of 80% projects. The last 20% — the final polish pass, the presentation render, the breakdown image — is the part that demonstrates professionalism. Finish three things completely.