I've been taking a friend through Trek, but she wanted to start with DS9, and then watch VOY. In order to make sure she didn't miss anything, we watched through character-focused TNG episodes in marathons that follow characters that would be appearing in the later shows. We did O'Brien and Worf ahead of DS9, but the Barklay marathon was my favorite. It was so fun seeing her go from not being able to stand him, to loving him when we got to the end of Voyager. I think Barclay is a very well written character