An alternative way, that makes the "1"s a bit less ambiguous, is to draw a bar a...

An alternative way, that makes the "1"s a bit less ambiguous, is to draw a bar at the bottom. So even if you put the serif on the 1, and write it sloppy, you still have the bar at the bottom.

See the last example in this image:

https://upload.wikimedia.org/wikipedia/commons/thumb/e/ee/Ha...

Side note to OP and author, the Wikipedia page is pretty handy and has a lot of info:

https://en.wikipedia.org/wiki/Regional_handwriting_variation