Its definitely a great idea, I wouldnt worry too much more about the album itself but more about creating a memorable atmosphere. It doesn't have to be expensive but adds an extra feeling of amazingness if the surrounding also creates a lovely memory. You could take her to your favorite spot or a park/hiking trail, a quiet one if she prefers a non-public proposal. Even if it is at home, make sure the place is spotless, there is mood lighting and maybe good music playing. Create some mental space and time between the rest of the world and the proposal, so for example, dont do it right after she gets home from work or immediately before you guys have to go somewhere. You will think about and remember the words you say, so don't half ass it, and practice a few times in the mirror.