The main way to maximise your State Pension is to increase the number of NI qualifying years.
But if you’ve already retired and you’re on only a low income, you might be eligible for Pension Credit, which will top up your weekly payments.
If your husband, wife or civil partner dies, you might be eligible for extra pension payments based on your partner’s pension or NI contributions. But you will only be eligible once you reach State Pension age yourself and will not be entitled if you remarry before then.