I'm compiling a list of the best and top most essential basic components an electrical and/or mechanical should have in their toolbox or catalog. Think WHO list of essential medicines. But I wanted the more experienced users take on what an electro/mechanical engineer should have on them.
Thanks!
The first, is a multimeter.
A soldering iron.
Tweezers.
Magnifying glass.
Screwdrivers, preferably VDE and a mixture of X & | point.
Sidecutters
Pliers
Knife
Various Spanners (for mechanical engineer).
The list goes on...
I realize now that you asked for components and we all starting talking about tools.
For components... if starting with NONE, I would recommend buying Velleman assortments.
For passives:
And Semiconductors:
Transistors
They also carry a nice assortment of diodes.
These packs will flesh out your collection so you can reach for a part when needed versus waiting on slow boats from China.
I tend to pick parts that are pretty generic and then by 25 or 50 etc. at a time. You will find there are some pretty common parts that can be used for many of your projects (I tend to pick parts with higher ratings than what you normally see - for example for my stash of diodes, I have a bunch of 1n4007 - 1A at 1000v - the price is typically about the same as the 50 volt versions but can be used anywhere, I have a bunch of IRL520 HEXFET power fets that I use to turn on and off various loads (Logic level drive, 100v, 9A) and switching NPN transistors like the 2N4401 (40v, 600ma - they were 4 cents/ea from Jameco for 100 of them (TO-92 case). You always need a bunch of 0.1ufd ceramic caps for bypassing things (usually right next to the chips from power to ground). For resistors, I have a bunch of 100, 220, 330, 470, 1k, 4.7k and 10k resistors which will cover most of what you do for either current limiting for LED's or pull-up resistors. What I have found works well is a bunch of 4 * 6.5 inch antistatic (pink) bags that I put my parts in and they are just the right size to put a folded 4*6 notecards in that I write the part number and basic ratings/ pin-out on, fold the top of the bag over and use small binder clips on them. File them in a plastic bin that makes for easy access. Makes it easy to find the parts, grab one as needed and go from there. I tend to sort of design in reverse if you will - designing something based on what I have in the "junk drawer" rather than looking for the optimum part then trying to get my hands on it. Jameco.com is a decent place to buy things from - check the prices for bulk - often the price for 100 of something (resistors, diodes etc.) is about the same as 20 individually priced.
The most important things he should have are a good brain and a good pair of eyes. Oh, and the ability to think out of the box.
Russell.
Need to be comfortable solving problems.
Know how to read & understand a datasheet.
Know to use an oscilloscope and be able to draw a schematic.
Some images:
The ability to know what a component is? 
pwillard:
I realise now that you asked for components and we all starting talking about tools.
Well he did say "toolbox" first. I don't know about you, but I do not keep components in my toolbox, and you do need tools to work with the components. 
I do believe we have accepted my reply #1 as a "given".
Resistors, caps (ceramic and electrolytic - you can skip the tants; they're expensive, and you can usually use ceramics or electrolytic), signal BJTs, signal fets, power fets (logic level), solderable prototyping board (hey, I sell those), wire.... LEDs, diodes (incl schottky), voltage regulators (3.3 and 5v), some cheap DC-DC buck and boost converters from china via ebay (they're so cheap - $1-2 a pop for the entry level ones). I'd say an I2C EEPROM too, AT24 series (for verifying that I2C works). Some TTL serial adapters (CH340G ones are dirt cheap) and (if working with AVRs) a USB Asp. Lots of 0.1" pin header and dupont jumpers - it's amazing how fast those go. A case of beer, too - that's important.
I have a bag of many strips of assorted SMT parts. It's been pretty indispensable. I agree about the toolbox thing, I don't keep components in there. In the old days, the components would go in those stacked small drawer cabinets.
aarg:
I have a bag of many strips of assorted SMT parts. It's been pretty indispensable. I agree about the toolbox thing, I don't keep components in there. In the old days, the components would go in those stacked small drawer cabinets.
That's what I still use - it's a real pain in the you-know-what to get the good ones though. They don't make nice metal framed ones anymore, just plastic crap. We buy them whenever we see them (surprisingly, they're often sold for the contents). I've got 10 drawer sets older than I am, filled with parts >.> And like as many plastic ones, empty and sitting in corners, which I try to sell to anyone who visits me for a fiver each, largely without success.
For SMD parts that are tiny, and which you don't have many of, I use the little lip-gloss containers, like these: http://www.amazon.com/Quality-Empty-Plastic-Cosmetic-Containers/dp/B00J7A4SAW/ref=sr_1_1_a_it?ie=UTF8&qid=1457134125&sr=8-1&keywords=plastic+container+lip+balm (those are the ones I used - lots of sources with lots of slightly different options. Try to get all the same kind, unlike what I did - even ones that look very similar don't have interchangible lids). Then those go into the drawers.
A pair of eyes.
Paper and pencil.
A multimeter, (it does not need to be expensive).
That's enough for arduino to start.
A soldering iron, that is worth saving up for a decent temp controlled one.
A willingness to know that someone may know more than you and respond to questions asked.
For mechanics/ electronics there are a lot of specialised and expensive tools out there.
Basic tools such as cutters ,screwdrivers and spanners to start with.
On this forum a phone with a camera is very useful too.
Boardburner2:
A pair of eyes.
An extra pair sometimes helps, too.
For components, just get the things you need for a particular project. But get twice as many - that way, the more projects you do, the more stuff you'll have on hand (plus it's stuff you'll know how to use.) For someone just starting, a beginner's kit is good. It usually comes with examples so you get some guidance on what to do.
My tool box is similar. I buy the exact tools I need for a particular purpose. Kit tools are often crap. Here are some of my tools:
Looking at your pix i suspect you have been a plumber , electrician, , drainage engineer, father , builder teacher.
EDIT
Looking at one , maybe a dentist.
Amateur at all of those except I do teach professionally. And the dentist part was limited to pulling my kid's loose teeth out when they were too squeamish.
Dental picks used to be very handy (still have a couple) back in the days when we wire wrapped everything. You used the picks to get out the ends of the wires etc. when you had to make changes and unwrap the wires. Very handy for poking around and moving the wires to see just where things went when trying to verify wiring too. Not much these days As far as tools go though, especially with the sorts of things we tend to do with these little processors and their support stuff, I would put a scope on the list right behind (but not very far) the multi-meter. You can buy a decent digital scope these days quite reasonably (my first scope was an Eico 460K that I bought for about $100 when I was earning less than $1 an hour and assembled it myself. Tube model - still have it downstairs :o )
