hang a picture of the two of you. smell can trigger memories, if she wore a certain perfume or hand cream [for instance, my great gram wore baby powder and a lot of foundation, so if i smell make up or baby powder i think of her] try keeping those smells around your house to remember things. better yet, you could try making a dream pillow with that scent the smell can help you dream about her or unlock memories. be sure to write down whatever you remember so you don't forget again. try making a memory box, fill it with picture of the two of you and stuff she liked. perhaps even things you made together.
other than that, you can try talking with her when Samhain rolls around next year. [unless her spirit has left summerland and she's been reborn] light a white candle and place it in your window, set an extra seat at dinner, and invite her in. later in the evening you could try skrying or pendulum work to try and speak with her.
i'm sorry to hear your friend passed, but just keep in mind, you can remember her forever, try to accept and move on, sometimes a spirit can linger here because someone they were close to in life refuses to let go and for whatever reason will remain here.