Rivail has given you an excellent and orthodox recommendation and explanation!
Traditionally, Hunter = Skinning + Leatherworking, precisely because you can make some gear for yourself.
I will say that this is much less compelling now than it was in the early expansions, because the usefulness of crafted gear is now less than earned gear, unless you are doing higher group content.
To make strong (say, Heroic-level) gear, you pretty much need material drops from Heroic raids. So do not rely on LW to provide you with any significant amount of gear that is stronger than you would get from World Quests at max level this expansion.
Personally, I have found crafting professions pretty much useless this expansion. They can be great if you devote attention and time to maxing them out, and doing higher content, but only a minority actually follow through with all that. For the rest of us, it’s like buying a gym membership on New Year’s.
As Rivali said, Herbalism + Alchemy is fine for Hunter. Actually, Herbalism + Alchemy is fine for everybody, since everybody can benefit from potions and flasks.
Now I would ask the question: do you ENJOY gathering? Can you spend a pleasant hour or two every week just gathering and sightseeing? If you can, then double-gathering is an option.
Herbalism + Mining is a way to pick up pocket money while doing your rounds of world quests, without committing to the course of learning a bunch of recipes in crafting professions. Mining because several of the older ores from previous expansions still sell to make older stuff, mainly mounts. Fel iron and Ghost Iron Ore, for example, always have a market.
I wouldn’t agonise too much about the choice. Just go with what you feel.