XCOM: Enemy Unknown

[Annubis]

You want to wait. That mission is pretty brutal.
I'd say you want laser weapons on everyone and a support that has 3 medkit if you want to bring anyone home from it.

[Yoda]

Yea I got it very early, just after my 1st terror mission?

Is there a time limit to this game? Can I take my sweet time upgrading?

[Annubis]

The only time limit is as long as you can keep the countries on your side.

[Klyde Chroma]

Upgraded armor (to whatever you can manage) two assaults with run and gun (plasma weaponry), 2 snipers (plasma weaponry also), a heavy weapons user and freakin' hero of a medic was my recipe for success in the first base mission.... actually that was pretty much my recipe for success for every mission... i can't stress enough the upgraded armor thing though... as soon as you can get decent/improved armor on your troops do so!!

Actually on that note, I prioritized my research early on as such.
1st priority: Armor
2nd priority: Weaponry (for troops only, I didn't even bother with the mobile weapon platform unit types until my troops were all decently equipped)
3rd priority: anything that had to do with craft technology

This allowed me to keep my troops alive, advancing in rank well enough to make latter missions far more manageable.

Another important strategy I found helped me sail through without too much trouble was making an excess of satelites long before actually seeing a need for them. First time through I didn't do this  and, believe me, there will be instances were you WILL need them without enough time to produce and launch them..... next thing you know missions pop up around the globe and you find yourself essentially gritting your teeth deciding which country you don't want to withdraw from the council... 

[Yoda]

Kylde, does upgraded armor take over the usual stuff equipped or does it count as a backpack item?

[Klyde Chroma]

Kylde, does upgraded armor take over the usual stuff equipped or does it count as a backpack item?

New armor takes over originally equipped armor. The only exception that takes a backpack item spot (that I recall) is the vest that is available very early on. The vest sucks but you can stack the defense bonus from using the vest WITH the armor.... If memory serves the vest only adds like +4 health or something which isn't too helpful later, but earlier on in conjuction with the first armor upgrades it can be pretty useful.

If there was an upgrade to the vest that takes a backpack spot I never got it.