Autodesk's Jeff Bartels walks through the more advanced options of Civil 3D Sample Line creation and manipulation with a focus on how to employ the grip options.
From the Jeff Bartels YouTube Channel.
and the Civil Immersion blog.
This is a good walkthrough of Civil 3D Sample Line mechanics that includes some of the the more advanced options and edit capabilities that can get lost in the shuffle.
Here's a tip. You may find it handy to keep really different Sample Lines in separate Sample Line Groups since you also often have to publish them separately anyway.