My general recommendation is to not interact much with Artisan Professions when leveling.
It is a lot more valuable to gain experience, reach level 60, and then use your increased gold, resources and mounts to focus on professions as it will be a lot faster.
With that said, there are still a lot of reasons you, as a player, might want to interact with Professions, be it early game, camping buffs, gathering herbs/ores/leather as you level, or simply just for fun.
Paladin is also very efficient at gathering thanks to the mounted speed from
Pursuit of Justice, so if you're looking to make tons of gold at 60, it's not bad to keep it up while leveling.
Blacksmithing
Is a great starting profession alongside
Mining, as you gain access to
Rough Weightstone, substantially increasing damage done early on.
Copper Deposits are abundant in the starter zones, enabling you to easily craft starter gear, including
Gemmed Copper Boots (BoP) and
Heavy Copper Maul with some luck or a quick visit to the Auction House.
Sadly, Blacksmithing rapidly becomes incredibly expensive to skill up, at a much faster rate than Mining, so unless you go out of your way to explicitly farm a lot of ores, it's best to leave it be past the starter zones.
You also quickly get access to
Sharpening Wheel, increasing your strength when camping which scales with level.
At level 60, there is high reason to believe that Blacksmithing will be very useful, as there are a lot of new crafted gear, including Tier.
Mining
If you plan on keeping Mining at level 60, you can absolutely go out of your way to skill it while leveling.
As a miner, you also get access to
Lodestone, which doesn't stack with
Blessing of Might, but allows you to run either
Blessing of Kings or
Blessing of Wisdom on yourself instead.
Engineering
This has historically been the late game profession, and will most likely still be.
While a lot of things have been made non-exclusive to having the profession, there are still a few things that still require it.
Additionally, while leveling you can access to explosives amongst other things.
It's also substantially cheaper to level than Blacksmithing.
Herbalism
Great to skill while leveling if you plan on keeping it at 60.
Grants access to
Incense Candle which is nice, but does not beat out other camp buffs.
Cooking
Cooking will be vital to have when leveling, as most food created with the profession will offer you a 5% experience increase from killing mobs when Well Fed.
But, this XP buff does not scale with the level of food, therefore it's not necessary to skill it too high.
By fighting beasts when running around in the starting zones, you should have plenty of meat to last you a very long time.
It also allows the crafting of
Basic Campfire Kit, which is needed to set up a camp for your other camp features.
Fishing
Fishing is a great way to easily level your cooking and make food, although if this profession isn't for you, there's not much reason to interact with it while leveling. Fish if you like fishing.
Also grants access to
Fish Bowl, it doesn't stack with
Blessing of Kings, but does stack with
Blessing of Might.
First Aid
First Aid has been given a lot more functionality, such as being the profession responsible for Healing potions, albeit with a new reliance on herbs from Herbalism.
It's a great profession to spend your cloth on, as bandages are always useful, even as a class with healing, it doesn't cost mana.
Grants access to
First Aid Kit, which is nice, but does not beat out other camp buffs.