No problem, a petition could also be verbal, you don’t have to write it on paper.
The same as you did before. Call her name several times after lighting a candle with glass of water or alcohol next to her picture or statue or sigil… then tell her your intention, thank her for her help, then leave the offerings ( candle and drink + anything else you wish to give as a gift ) and take them away next day or after couple of days.
Would be great to talk to her and thank her as long as the offerings are on her altar. She’s not just there working for you… treat her as guest in your house. Talk to her, thank her, make sure everything is clean around her statue etc That makes your relationship with her better, and the results of your work with her better.
About “do and forget” … you forget about “asking” for what you want all the time. You don’t forget about her. You have faith that what you asked for is going to happen, give her thanks and show her your appreciation and gratitude for that. You can make it a one-time prayer… but that’s - honestly - lazy. Depends on how important your request is, I guess. If it’s important or urgent then keep your connection with her about it until it happens. If it’s not that important or you don’t mind the delay… then just give your request once and forget about the whole thing and wait.