Want to work on my portfolio

for context: i just graduated from my technical college with a diploma in architecture with bad results. however the university i want to apply takes considerations if you a good portfolio.

i want to work on my portfolio to boost my chances of getting into this university, what workflow would you suggest i go with to start? should i use the usual bim programs or is there a programme i can use that can do everything from modelling to exporting and creating good portfolio pages.

im not working so it would be great if it was budget friendly as well!