To start off with engineering you need to be level 5. You also need to find yourself an engineering trainer. (go figure!)
Every major city has an engineering trainer, so you can get started there. Just ask a guard to find out where to find one. Buy a blacksmiths hammer at a nearby trade, blacksmithing or engineering supplier. You’ll need it later down the road.
What Profession To Take Alongside Engineering
Pick mining. The majority of the items you make will require a type of ore, stone, or both.
If you really want to pick something other than mining, expect to pay a lot of money to buy the ingredients you need to skill up your engi.
The next best option would be skinning, as a number of engineering schematics require leather. By selling the excess leather you could generate enough income to buy other ingredients, but I can’t recommend it. You will have a much easier time skilling up with mining.
If you choose to get mining, you’ll need a mining pick. You can buy it from a mining, engineering or trade supplier.
First Steps
It’s easiest to level a profession if you actually start at level 5, because it is simple to progress the skill as you level up. If you are of a higher level, you will need to go to low level zones to farm ore to obtain the necessary ingredients and skillups. See chapter 2 for information on good locations to find your ore. If you picked up mining at a low level, you will be able to keep your mining and engineering skills high by just mining the ore veins you come across, without having to go out of your way much to look for them.

Keep all the ore, stone and gems you find. Chances are that if you don’t need any of them immediately, you will need them later for one schematic or another.
Useful Engineering Schematics At Lower Levels
As your skill gets higher, you will get access to many cool gadgets and devices. But, there are certainly useful things to be made at the lower levels.
The most important thing here is explosives. These come in two varieties:
Bombs; Deal damage and add an disorient effect, which disables targets for a short period. The time your enemies spend stunned can be used as a means of escape. Note that damaging the target will break this effect. The ability to get a few yards between an enemy and you before the effect wears off can make all the difference.
Dynamite; Purely does damage. Requires slightly less and easier to obtain ingredients than bombs.
Both can help you add some extra damage to a fight, and can decide a fight in your favor.
If you are capable of using guns, you may find some useful ones to make at the lower level range, and up your damage a little by adding a scope to your ranged weapon.