I typically use the following loadout (Mostly because I'm too lazy to change between missions)
2 GL's
3 Assault's
2 Close Combats
1 Heavy
Everyone carries a medkit in their backup
My assaults carry, Assault rifles first, then lasers rifles and typically provide bases of fire. 2 spare clips in belt (7.62 pistol, 2 nades in holster) and the usual medkit, sort of my jack of all trades master of none. Thou given the lack of a sniper on my team, (and some what.. questionable results of a single heavy) they are often relegated to long range support as well.
My close used to carry shotgun + spare rounds + (Pistol + 2nades in holster) + 3 nades in backpack
Now they use a single laser pistol in hand + nade in hand, 2 clips in belt, 4 nades + knife in holster, 3 nades in backpack (and the usual medkit)
They form the basis of my reaction fire close range, long range medics, and indirect nade support (where a GL can not reach, e.g. over the mountain in the crashed harvester mission)
They nade in hand is the single coolest tactic ever, as often a single pistol/shotgun will not get you a kill. What explosives do however, is cause fear in the enemy, which when combined with the direct fire from the pistol and support from friendlies, will cause the enemy to route.
The heavy is basically a machinegine/similar upgraded version
Right now it has a heavy laser, (pistol + 2 nades in holster) medkit, 2 clips in belt + extra clip in backpack. Personally I find *limited* use for the heavy. I find it does supress enemies *slightly* better then my other guns, but never enough to make it a tactically viable weapon. (In greater numbers it might perform better, but I would loose too much versatility if I keep transfering assaults to heavies)
And my GL specialists. My "best" (highest ranked) soldiers with the most kills.
Given the AI's "tactics" (they use hit and run mostly) it usually means they are around the corner which makes them prime targets for a bit of indirect fire.
Grenadelauncher, 4 grenades launcher nades in belt, (usually 1 is fletchet, the rest are he/pb when available) (watching a triple shot fletchet is on of the most awesome things... ever Its like a super shotgun...)
pistol + 2 hand grenades in belt
3 more grenade launcher grenades in the backpack + the usual medkit
Standard tactics are as follows
For long range engagements.
My close combats, drop their nades and pick up a medkit
Grenade launchers are dedicated medics
Assaults and heavy provide most of the fire
Typically. I try to get 1 assault + medic, to stay at extreme range and provide overwatch, drawing fire from the enemy (and given the range, they are mostly safe from instant kills, and the constant medical aid allows for continuous watching)
Then the rest of the team is deployed closer up to score kills by hit and run. So my overwatch might spot an alient rushing, and then 3 guys pop out from behind a wall and pop the rusher.
In Close combat
Usually I have no dedicated medics (as the short range does not allows you to disengage) (thou if required, I tried to make the heavy do medic'ing as he is the least useful)
Stunning your own guys who are exposed and out of TU's is a great way to save them! (Careful not to choke your whole team thou.... "lost" 3 guys once from that...)
Close combats naturally lead the way. (Toggle reaction fire depending on the circumstance) with grenade launchers as seconds, usually using goggles when not firing. If assaults are present, they become the number twos, whilst GL's become threes (thou GL's still use their goggles, 1's and 2's never use goggles)
The heavy is usually never in short range combat, unless he is a dedicated medic/goggle'er
Med Combat
Hit and run + grenades. All direct fires provide fire superiority, whilst grenade launchers score the majority of the kills. (This requires superior numbers/positioning/choke points thou e.g. 6+ members overwatching the exit of a UFO harvester). If I can not get fire superiority, I will use hit and run/shoot and scoot, / indirect fire and less(/no) overwatch.
Usually no dedicated medics
I do not use snipers, and I have minimal reliance on direct fire heavies (I just hired him because he had an insanely high initial heavy proficiency)
I typically build a load out around the soldiers skills, not around my desired loadouts. (i.e. I find the best soldiers first, then give them their best weapons)
A side effect of my loadout however, is that the close combats have fairly high explosives as they throw lots of grenades. (I try really hard not to nade with my assault/heavies, as they tend to miss.. which hurts my guys quite a lot)
Some other funny tactics I do, is to hit an ortnook once (e.g. with a poorly place grenade), and run behind friendly troops/walls. It will get angry and in it's rage, will rush my well prepared team and die.