Potion/alchemy vials- they need to be a certain size, but don't need to be filled. Most people carry a few extras with them to game, and anyone who makes potions/alchemy brings a lot extra since we use a lot. I personally just order test tube vials in bulk to split with other people.
From my experience...
Potions and scrolls are useful to have rarely used spells on hand without memorizing them. Alchemy has unique weapon coatings and gases that allow you to turn coin into extra firepower when you need it. Blacksmithing is either you getting one rank to be able to fix armor, or twenty to get the bonus ability to repair armor faster- the rest is kinda just OK unless you have other skills to back it up.
Traps- they can be really useful in the right place and time, but you need to wait to find that time. Just 4-5 ranks will allow you to make area effect traps, which you can set up in battle (either at a lull, while getting cover from a friend with a shield, or in preparation before the fight or when falling back) Doing up to 50 damage in a 10 foot radius is really effective in taking out a wave of enemies. Plus, massive mechanical traps are one of the few things that allow players to do massive damage- which allows you to hurt enemies hiding in wards and circles of power. So, not useful all the time, but really useful at the right times.
If you do want to do lots of crafting, it is very helpful, but make sure you also take a weapon skill to defend yourself with too, for when you can't avoid a fight.
Just my two cents.