Hey friends the process is super shady no joke!! there is a lot of luck involved and connections matter more than they should. i think the most important thing (beyond grades) is your connection with your POI
good to connect early, be able to demonstrate compatible research interests (through projects, volunteering, etc), and if your current supervisor knows them somehow, even just barely, that is very helpful.
Also applying for funding, having lots of research experience, etc
Don't give up!!