If you wanna avoid a lot of spoilers from comments, in a nutshell you should take some time to gain experience/expand your base before doing more story missions, or you will be in big trouble :D.
you guys are spoiling the game though the game gets harder the further you go not just doing alien abductions but it gets harder each time you do them i remember UFO defense being hard for this at least they kept the difficulty for enemy unknown but the game starts to easy at the beginning
Alloys, Weapon Fragments, Ellirium, UFO Flight Computers, UFO Power Sources, Fusion Cores and the rare alien corpses *Berserkers, Sectopods, Ethereal, Sectoid Commander, Cyberdisk* Are probably the things you should never sell. The rest is more or less expendable. Sectoid and Thin men are important for building Interceptor upgrades, but they are the most spammable unit on the game.
You got incredibly lucky on your Alien Base raid. I had to fight 8 Cryssalids, 2 Cyberdisks, 6 Mutons, 2 Berserkers and 1 Sectopod with a squad of 6 Drones. Plus 2 panicking soldiers and one critically wounded soldier that, although saved he was useless for the rest of the mission as critically wounded soldiers cant fight.
BTW, you shouldnt rush through the main storyline missions, neither your troops nor you can deal with squads of elite alien units. Now that you destroyed the alien base, you will start facing Mutons and robots more often, you wont fight thin man or sectoids anymore. Your low ranked and crappy armored soldiers wont last. Even your Colonel wont last without the Titan Armor.
You should start building Firestorms, as no longer you will face scouts or small alien ships. You will start fighting on Abductors and Battleships.
Also if you rush through the storyline missions you wont be able to get enough materials for high-end plasma weapons for your soldiers and fusion missiles for your Firestorms.
The most important thing you should do right now is rebuild the Foundry and start researching weapon and equipment upgrades. And also research the SHIV project. The SHIV is probably the best unit on the game after full upgraded Colonels and Psy soldiers. Plus its cheap so you can spam it on the battlefield.
You should spend at least a year of the game just taking regular missions *Abduction, Council missions, Terror missions* upgrading units, building facilites and gathering resources and making research and ignore the main storyline missions. If not youre going to get raped by the aliens. also give your Arc Thrower to your Support since he can carry 2 things instead of 1.
Oh, yeah and i forgot. Build Workshops, workshops makes making weapons, building Firestorms and SHIVs and building facilities much cheaper.
Sorry for the long post and the spoilers, but i dont want you spend so much time playing the game only to get the YOU LOSE screen. It happened to me on my first playthrough and it pissed me off and i played on the same difficulty as you, so it could happen to you if you rush through the main story missions.
Stalin the next thing you can get is a psi lab where you can see if your soldiers have psi abilities. very useful and the first one is scripted to have psi abilities.
lol commander thinks its over. Yada yada, eye of the hurricane, etc.
Hopefully it's not too late to train redshirts on the easier missions; what if you get stuck at long range combat with mostly shotgunners, for instance? ... There is no reason not to sell a lot of specific items ya aren't using, they aren't all as important as alloy. You're one excavation away from the heat-power, and you can make special elyrium up-links if ya want.