is it in nissan? because i think that you may want to check if you are allowed to fast.
jewishmourningguide.com/yahrzeit/yahrzeit-outside-shul/
yahrtzeit candle
fast (but say it’s only for this year)
give tzedaka-
try to have as many siyumim as possible
give ‘tikkun’ (whiskey,orange juice, coffee cake, rugelach)
get inspired to do teshuva in the niftar’s zchus.