See here a picture of the omote side of the recently wrapped tsuka. "Omote" means the front- or showing side whilst the term "Ura" refers to the hidden, inner side.
You can easily find out which side of the sword is ura and which is omote:
Picture yourself wearing a sword (katana) on your left hip through the obi. As with katana, the cutting edge will be pointing upwards.
The tsuba resides in front of your belly button so people in front of you will see the left side of your sword handle.
This side is the omote - the showing side, with ura being the side close to your stomach.
On a Japanese sword handle, the ura and the omote sides have their unique features. Inside the last hishigata (diamond shape) on the omote side you will sometimes see a large emperor's pearl (oyatsubu) of the ray skin. The placements oyatsubu and the specific knots for each side are examples of the many hidden details of the Japanese sword.
When restoring a long tsuka, the most important task is to have good preparation: measuring, calculating and marking are the keys to a good wrap.
For example tsuka-ito measures a 10mm relaxed width but can be pulled so the width drops below 7 mm. You want the wrap to be as tight as possible, but more important is to have consistency in the wrap.
This handle has 39 strips of tsuka-ito so the ito covered area should be 39 * 7.5 mm = 292.5 mm. The 7.5 mm width is my personal average with when wrapping silk.
If two of the 39 strips are wrapped too tight (let's say 7 mm), I have created a deviation of 1 mm and I will have a gap at the kashira.
Gaps caused by a deviation in widths are often fixed by changing the ura and omote knots of the tsukamaki (by adding another strip). While this isn't wrong in a practical sense, it is not correct in terms of the Japanese sword tradition.