On my Heavy tanks, my loader and radio operator were trained first in Repairs. Driver gets Off Road Driving always first (you're going to be spending about 70-85% of your movement in this environment.) Gunner got Snapshot, because -- better aim is more hit efficiency which equates to more damage. Commander Recon. In pretty much all other classes most of these first skills would probably be Concealment. Hvy tanks have the worst concealment and you get the least bang for your XP buck by taking concealment for a Hvy right away.
For 2nd skills, those that didn't take Repairs will take -- you guessed it, Repairs. So now Driver and Gunner take Repairs, Loader takes Firefighting, Radio takes either Firefighting or Situational Awareness (if I am in a slow tank, Firefighting -- a fast one SA) and Commander takes Repairs.
In Hvy tanks you end up getting pounded on a lot from just about anyone who can hit you. Even those "useless" bottom tier tanks are busy tracking you and keeping you spotted, sometimes popping an evil round into your engine compartment. Repairs on your crew is a more useful skill than Concealment for a Hvy tank in most cases (there will be that one or two exception units in most every class) as you will be expected to brawl and if you don't they will hunt your butt down. You need to get damaged/destroyed modules/components back up rapido, rapido!
I haven't changed my consumeables load yet, but I think I may dump my small repair kit for a toolbox (speeds up repairs and stacks with crew skills, which are cumulative across entire crew with them, similar to BIA, except that it works all the time) and see what kind of difference that makes. As I can unmount it once I get it, like nets and binocs getting one wouldn't be a big deal as a test. Once I jump I'll report back and see what kind of difference it seems to make.
I also recommend you carry an Automatic Fire Extinguisher. Not only does it automatically put out a fire when it happens, it reduces the overall percent chance to even HAVE a fire by 20% just being on your unit. Combined with Firefighting on your crew (another Cumulative Skill across the entire crew that stacks with fire extinguishers and improved engines to reduce chance of fire) this can pretty much reduce your chance of fire to something like -- well, I caught fire three times in the last hundred or so matches maybe? Maybe less. This is inclusive of not catching fire with an ammo rack explosion once. Firefighting and Fire extinguishers are worth it.
This is all hindsight selection. When I first started selecting skills I chose a few that didn't really make sense -- such as concealment at first for my heavy tanks. Not useful, because it just didn't make enough of a difference to be a factor in my survival. So when I managed to get a third skill going on my first Hvy crew (still in my US T1 Heavy Tier V) that I brought up from the M3 Lee Medium, I switched to BIA 1st for all and then the selections above. Any of you who have yet to get that far, now would be a good time to think about your most useful crew skills for the types and classes of tanks you want to play the most and focus on those.
Definitely you should go to the wiki at the very least and read up on the whole Crew Skills outside of the client where you can do comparisons without a tank crew with a + sign urging you to CHOOSE NOW flashing at you. Think about what you expect to do and what you will attempt to accomplish in your tanks and outfit your Crew Skills accordingly. Remember, you can reset your Skills and Perks, either with gold or silver (the silver option takes a 10% or such bite per skill reset I believe, so resetting 3 skills would cost you 30% off your 3rd skill, keeping the first two entirely intact) and select new Skills and Perks. This is when you take your 1st Skill in your crew and switch it to the Perk: Brothers In Arms, which only works at 100% and is required to be on ALL CREW to work.
The BIA bonus is very notable right away. It's worth the hit even if you can only retrain or reset with silver like myself. In such cases, just make sure that the last skill you are resetting is at least 50% before you do. That way the hit doesn't suck the last skill down to nothing. You probably will only completely reset a crews skills in this manner once ever. By then you'll know what you're doing from there on out and your reset will reflect that knowledge at that time.
Hope that's useful and relevant, I'm too tired to play and so am haunting the forums for my 'entertainment.' Pretend I'm like a documentary.
GL, HF & HSYBF