Make your details match everywhere
Use exactly the same name and date of birth on every loyalty account you might link. Avios lists matching personal details among the first things to check when accounts will not link.
Link accounts before you need them
Avios requires accounts to have been active for 30 days before moving points, and Amex says new partner links can take up to 14 days to verify.
Find the reward first, then transfer
Search for reward availability before converting or transferring points. Transfers out of Membership Rewards cannot be reversed, and conversion rates between programmes are set by the programmes and can change.
Keep Avios active
Earn, spend or buy Avios at least once in every 36 months: the Avios terms say your Avios expire after 36 consecutive months without that activity. Moving Avios between programmes does not count.