What the scoring models weigh
Payment history and credit utilisation carry the most weight in widely used models, followed by the length of your history, the mix of credit types and recent applications. Everything else is noise by comparison.
The reliable levers
Pay every obligation on time, without exception. Reduce revolving balances relative to limits. Check your reports and dispute errors, which is free in both countries. Keep older accounts open where there is no fee. Space out applications.
Advice that does not help
Carrying a balance does not improve a score, and it costs interest. Checking your own report does not lower it. Closing an old card can raise your utilisation and shorten your history. No legitimate service can remove accurate negative information.
Products designed for rebuilding
Secured cards and credit-builder loans exist specifically to establish a payment record. Confirm before applying that the provider reports to the main bureaus in your country, since a product that does not report cannot build your file.