Why 1 crafting and 1 gathering per char is a waste of time. . .

I see this theory all the time: if you are taking a crafting skill, take the corresponding gathering skill. Blacksmiths, jewelcrafters, and engineers take mining; leatherworkers take skinning; Alchemists and scribes take herbalism; enchanters take tailoring by default. What is wrong with this reasoning? It is the absolute least efficient use of a character you can have.

First of all, for a single character just starting out, there is absolutely zero reason not to double gather. Mining and skinning is solid however my personal favorite is mining and herbalism. Mining and herbalism is a more advanced version because you can only have one or the other show up on the map, but once you master it, these are much more profitable and used by a larger number of professions (3 and 2 to 1). So if you only have one character, do yourself a favor and double gather, you will never be self sufficient, at least there is almost always a market for raw materials.

Still reading? This means you probably have more than one character. I can identify with that, I too have more than one character. If your goal is to be completely self sufficient and do it the most efficient way possible, you have to break your characters into two groups: gatherers and producers. The reason for this? Gathering takes time and if you can gather for multiple characters at the same time, you are increasing your efficiency. Here is another tip, classes that use similar resources should be grouped together. I like to pair blacksmithing and jewelcrafting. Why? You're only sending metal to one character (I dislike engineering, it doesnt do much for me and seems like comparatively a waste). I would say alchemy and inscription go together (they do, naturally) but like most people, I leveled up alchemy before inscription was introduced, so that wasn't very viable.

Personally I came up with two different models, one is a one gatherer model if you intend to ignore leatherworking and buy any leather you need at the AH (I don't like doing this, I like to be purely self sufficient, but thats just me). The other one uses one "pure" gatherer and one gatherer who has a crafting skill.

One gatherer:
Gatherer: Mining/Herbalism
Crafter A: Jewelcrafting an either blacksmithing or engineering
Crafter B: Tailoring enchanting
Crafter C: Alchemy/Inscription

Again, thats an ideal layout starting (mostly) from scratch.

Two gatherers:
Gatherer A: Mining/Skinning
Gatherer B: Herbalism/Inscription
Crafter A: Jewelcrafting an either blacksmithing or engineering
Crafter B: Tailoring enchanting
Crafter C: Alchemy/Leatherworking

You can tailor this to your liking, you can swap LW with inscription and make your herbalist a BS or engineer to give you an additional metalworking profession, it has a lot of possibilities. You could do herbalism with skinning and do JC with mining. The important thing is since you can only be gathering with one character at a time (unless dualboxing, but I won't get into that), do it as efficiently as you possibly can.

Lastly there is one more benefit of crafters and gatherers being seperated: rested experience. The best place to leave a crafter is near an auction house. Why? To sell the stuff they made. AH's are generally in capitals which give you rested XP. You only need to get to level 60 to hit the crafting cap. Let your crafters sit, quest with them when you feel like it getting the benefit of a full level and a half of rested XP.