Thou Shalt Not Pass is a secondary quest that sees you acquiring a transit pass in order to go through Redanian Border points. The only way to do this is to get the black market pass from a nearby merchant during the quest Fake Papers Guide contains image walkthrough and starting NPC location.

Deadly Crossing is one of the many Secondary quests in The Witcher 3. It gives you the chance to buy a weapon from a couple of looters.

Death By Fire is a secondary quest you can happen upon while exploring Velen in The Witcher 3. Guide contains image walkthrough and starting NPC location.

Last Rites is a secondary quest available in Velen, involving a bit of grave hunting.

Caravan Attack is a Secondary Quest in The Witcher 3. You will be tasked with protecting a trading caravan from bandits.

Harassing a Troll is a Secondary quest in The Witcher 3. To finish it, you’ll need to defend a rock troll from some nekkers. Guide contains image walkthrough and starting NPC location.

Forefathers Eve is a secondary quest available in Velen. You can do it after completing Secondary Quest: A Towerful of Mice, but before Main Quest: Family Matters. You can also go to Keira Metz’s cottage and start it there (if you completed Main Quest: Family Matters, and then Secondary Quest: A Towerful of Mice).The pellar will automatically walk up to you. Guide contains image walkthrough and starting NPC location.

At the Mercy of Strangers is a Secondary quest in The Witcher 3. In it, you get a chance to save a Temerian deserter from certain death. Guide contains image walkthrough and starting NPC location.

Highway Robbery is a secondary quest available in Velen, near the Boatmakers’ Hut.

Bitter Harvest is a Secondary quest in The Witcher 3. In it, you’ll protect a group of scavengers from undead monsters. It is also part of a group of quests that will grant you access to Redanian territory. Everything starts with “Thou shalt not pass” and continues with “Fake Papers” quests. Guide contains image walkthrough and starting NPC location.

A Frying Pan, Spick and Span secondary quest will have you searching for an old woman’s lost frying pan.

Faithful Friend is a secondary quest in White Orchard, available only during the epilogue of the Main Quest: Something Ends, Something Begins (II).

Deadly Crossing is a secondary quest that is available as you explore Velen and Novigrad during Act I.

Defender of the Faith is a secondary quest in the Witcher 3 that is available as you explore Velen.
Guide contains image walkthrough and starting NPC location.

Face Me if You Dare! is a secondary quest that is available in Velen. You will find yourself the unwilling recipient of a challenge from a delusional man. Guide contains image walkthrough and starting NPC location.

Nilfgaardian Lessons – Witcher 3 quest.

Missing in action is a Secondary Quest that is available in White Orchard via a Notice Board. You can help a soldier find the corpse of his brother who was killed in a recent battle. Guide contains image walkthrough and starting NPC location.

Twisted Firestarter is one of the first Side Quests in the game. Blacksmith Willis’ forge has been burned down and you have to find the culprit. Guide contains image walkthrough and starting NPC location.

Brother Missing is a White Orchard Notice board "side quest" that actually starts the quest Missing in Action (click on this link to see the full screenshot walkthrough)

Imperial Edict Number 18/45 – Witcher 3 quest.