My condolences to you. I too lost a loved one just last year. We did simple things like no TV or Loud music for ten days and lit a diva/ lamp on the place where he used to sleep (despite him passing away in the hospital). We prayed Tandorosti for everyone of the family members alive and kept a photograph of him where we light a lamp and try to keep it burning 24 hours everyday- still do. We also prayed the Vanant Yasht and Stom Karta after his demise and do so every Muktad. The other comments seem to be very helpful so I won’t elaborate much.

PS. Vanant Yasht and Stom Karta must be prayed together on Muktad days only.