That is adorable!
I sew with vintage patterns and have a very large stash. The instructions are usually pretty good, they generally instruct you to clip seams and under stitch and often have lots of notches to help match things up. They often don’t tell you when to neaten your seams, watch out for that.
The sizing can be very slim (a reason why I like them) perhaps lay the pattern pieces over clothing that fits?
The older vintage patterns (1940’s) often don’t have lines, they are plain paper but they are precut and have holes punch in them for marking transfer.
If the pattern is damaged or torn I find using scraps of tissue paper glued under the pattern makes a good repair and is still iron-able.
I definitely use my O+S grooming when sewing them, and they do compliment the O+S style well.
Good luck!
(my vintage work so far https://www.flickr.com/photos/motherof5/sets/72157632088421306/ if you would like a peep) š