Express Entry is the best program to get a PR in Canada. You get a score depending upon your education, work experience, IELTS or other language test result, age, marital status, etc. There are three main categories under EE:

1. FSW: you need to have experience from foreign country (outside Canada) to be eligible. Rest depends on your score. If your score is more than minimum cut-off, you will get invitation.
2. CEC: This applies to people who have Canadian work experience. Again, you need to have EE profile score more than the cutoff.
3. FST: only applies to people who have trade (plumber, carpenter, welder etc) license.

All the three streams require you to have some minimum score which is more than cutoff. Following are the main things, which will help you get best scores:

1. IELTS: get at least 8 in listening and 7 in all other sections.
2. Education: get a degree, diploma or certificate from a Canadian university or college or have your degrees from home country evaluated by WES or any other organisation to meet North American equivalent standards.
3. Age: if you are between the age of 24–29, you get max points in this.
4. Work experince: one year Canadian work experience is more than enough to get good points. Else, at least 2 years of foreign work experience.
5. PNP (Provincial Nominee Program): this is optional. If you go to specific province and apply for their PNP, then for PR application you get additional 600 points if PNP is approved. This will give you score which will most certainly help you get permanent residency.
6. Job offer with LMIA: this is also optional but if you can get a job offer which is supported by Labour Market Impact Assessment (LMIA), you will get additional 50–200 points and you will most certainly get PR.

I have tried to give you a basic idea on all the streams and what you could work on to get better points in Express Entry. Most of the international students study here, get one year experience and apply for PR after scoring good in IELTS. People with good experience from outside Canada either apply directly or if they lack points, they come here and study for a year or two which helps them getting enough points.

Hope this helps. Good luck. :)