Completing daily crafting writs earns you coffers of a certain tier, denoted by the Roman numeral after the name (e.g. Woodworker's Case III).
Investing skill points into the first passive in each crafting skill line will increase the tier of the coffer. For equipment writs, higher tiers raise the chance of getting a gold upgrade material (from about 3% at the bottom tier to 30% at the top tier).
All top-tier coffers also have the chance to reward Sealed Writs. It is (almost) always a good idea to earn the top-tier coffers. To increase the chance of Sealed Writs, learn traits. You can also fully learn some purple motif styles, but this can be expensive and it provides diminishing returns after the first few.
The main rewards from daily crafting writs are:
Leveling Enchanting takes a very long time without help. The fastest realistic way is to deconstruct green or blue Truly Superb glyphs that someone has crafted. Eventually, you will need to invest 9 skill points into Potency Improvement (10/10).
Learning enchanting traits is quite easy for any character to do. Addons, such as Caro's Enchantment Learner, will do this for you. If you want to learn the traits of all the Aspect runestones, you will need to temporarily invest 3 skill points and use a kuta, rekuta, and denata.
The best reward from the Enchanter's Coffer X is a Sealed Enchanting Writ. This is one of the easiest master writs to complete and the materials to do so are very inexpensive (except for any writ that requires Hakeijo). You must invest 9 skill points into Potency Improvement to earn Coffer X. The more enchanting traits you know, the higher the chance of getting Sealed Enchanting Writs. Sealed Enchanting Writs are worth quite a bit of gold and their value goes up during double XP events.
You cannot earn Sealed Enchanting Writs from lower-tier coffers (I-IX).
Leveling Alchemy can be a bit costly if you're not careful. The fastest way to do so is to craft the highest level poisons (not potions) possible, investing a skill point into Solvent Proficiency as soon as you are able to. (At Alchemy levels 10, 20, 30 and 40.) This will require a lot of reagents, so be careful to only use the inexpensive ones, such as Luminous Russula or Fleshfly Larva. And be sure to pick the highest level solvent when crafting. Eventually, you will need to invest 7 skill points into Solvent Proficiency (8/8).
Learning alchemy traits can be time consuming and a bit expensive, but worth it in the end. Addons, such as Lazy Alchemy Learner by Dolgubon, will do this for you. It is not worthwhile to learn the traits for rare DLC materials, such as Powdered Mother of Pearl, on your non-crafters.
The best reward from the Alchemist's Vessel VII is a Sealed Alchemy Writ. Similar to the enchanting version, this is one of the easiest master writs to complete. The more alchemy traits you know, the higher the chance of getting Sealed Alchemy Writs. Sealed Alchemy Writs are worth quite a bit of gold and their value goes up during double XP events.
You cannot earn Sealed Alchemy Writs from lower-tier coffers (I-VI).
Leveling Jewelrycrafting can be expensive. The best way to do this is to deconstruct crafted jewelry that is white quality and level CP150, crafted by someone else. The inspiriation gain is comparable to deconstructing intricate jewelry. Eventually, you will need to invest 4 skill points into Engraver (5/5).
Learning Jewelrycrafting traits does not affect upgrade material rewards. You can safely ignore doing this.
The best reward from Jewelry Crafter's Coffer V is the upgrade materials (grains/platings). The tier of the coffer (I-V) determines the chances of getting better upgrade materials, such as Chromium. Jewelry Crafter's Coffer V will have a guaranteed upgrade material in its rewards. It will also reward Sealed Jewelry Crafter Writs, but these are not worth much gold and rarely worth completing.
Leveling Clothing, Blacksmithing or Woodworking is quite easy. The best way to do this is to deconstruct all gear you find, especially intricates. You can also deconstruct crafted gear that is white quality and level CP150, crafted by someone else. Eventually, you will need to invest 9 skill points into the first passive of each crafting skill line (Tailoring, Metalworking, Woodworking) for a total of 27 skill points (10/10).
Learning Clothing or Blacksmithing traits takes quite a long time. There are 14 different pieces to learn traits for. Learning Woodworking traits is comparatively faster as there are only 6 pieces to learn traits for. Trait knowledge only affects the chance of earning Sealed Writs. While these can be sold for a decent amount of gold, they are not always worth crafting yourself, especially Sealed Clothier Writs. It is recommended to do trait research for Clothing, Blacksmithing and Woodworking. Motif knowledge also increases the chance of Sealed Writs, but has steeply diminishing returns after the first few.
The best reward from Clothier's Satchel (Cloth/Leather) X, Blacksmith's Crate X, or Woodworker's Case X is is the gold upgrade materials (Tannins, Tempers, Resins).
Leveling Provisioning is fast and cheap, but also unnecessary after Provisioning level 20. This is the one crafting skill that you actually do not want to fully invest skill points into. (2/6, 3/6, 4/6 or 5/6)
Learning purple or gold quality recipes will increase the chance of Sealed Provisioning Writs, but this can be expensive and is not recommended.
The best reward from Provisioner's Packs is the recipes. The recipes from bottom-tier and top-tier Provisioner's Packs are worth much less than those from mid-tier coffers, so it is a good idea to earn Provisioner's Pack II-V. If you do decide to fully invest skill points into Recipe Improvement, you will be able to earn Sealed Provisioner's Writs, but due to the cost of Perfect Roe, many of these will not be worth crafting yourself and also not worth much gold.
Doing daily crafting writs of any tier can occasionally reward crafting material surveys. (Note: The chance of getting a survey from coffers is not affected by invested skill points. It is flat 12.5% chance.) The gold value of harvesting a survey is extremely high compared to the time spent harvesting it. Addons, such as Map Pins, can help you find survey nodes easily. You can also do multiple of the same survey (in a stack) by harvesting everything, moving a certain distance away from the nodes, and returning to the area. The exact distance is different for each location, but it is much faster than traveling to each survey area one by one. The raw materials you get from surveys can be sold for a lot of gold or refined for the chance at getting valuable upgrade materials. If you are refining for yourself, be sure to slot the Meticulous Disassembly CP star (green tree) and invest points into the relevant crafting skill passive (Metal Extraction, Unraveling, Jewelry Extraction or Wood Extraction).
The gold reward for crafting writs can be up to 4,648 gold in total for all 7 writs. This is per character per day. It is scaled to your character level and can be increased with the Gilded Fingers CP passive in the green tree.