Pick projects with a purpose
Choose projects that solve a clear problem. A focused tool explained well says more than a long list of tutorial clones.
Show your process
Write a short case study for each project: the problem, your approach, the trade-offs and what you would change.
Keep code readable
Recruiters and reviewers often open the repository. Clear structure, a useful README and sensible commits make a good impression.
Present it simply
A clean portfolio page with three strong projects is easier to review than a crowded one with ten.