Anything else besides lighting a candle at the Catholic church for a friend who passed away?

I think I might have asked this years ago for another friend, I don’t remember for sure.

It’s actually the mom of a very close friend of mine. Her mom meant a lot to me. She was very religious so I wanted to do something in the church for her.

I assume I can light a candle at the church. Anything I should know about what to do or not to do? Anything else I can do while there in her memory?

Also, the last time I saw her a few years ago she crossed me when we said goodbye. What’s the correct way to say that in American English?

Thanks!