Credit scoring is used by banks and other institutions granting credit to consumers. The scoring differs between institutions as they may use different criteria. E.g. credit scoring for a clothing account may differ slightly from the scoring for a motor vehicle.

The scoring is based on research and data collected over many years. Typical factors will include property ownership, length of residence, salary, age, occupation etc. A property owner is less likely to abscond and long residence indicates stability etc.

There is no number to aim for. You have to basically build up a good credit profile over a period of time. As in anything in life, this takes time. Start small and build up a good name as a regular payer. Some accounts are easier to obtain than others, e.g. clothing accounts. Once you have paid a few instalments on time, they tend to up your credit limit. So you build up a credit record with traceable references.