My training program for my final raiding force is straightforward, but strictly regimented... (This is for the End Game strike force... otherwise it's a waste of resources/time, and makes use of Alien LOS issues.)
My initial squad develops normally, taking advantage of lucky pot-shots that may incapacitate and disarm aliens. (free target practice with belt-holstered sidarms... they always keep a pistol on hand for training purposes)
But once I have a Training Base begun (basic interception base with an emphasis on Psi-Labs and multiple Skyranger hangers) I take note of any Floater Bases for not only Supply Ship commandeering, but also for fast-track training for my fresh recruits.
I outfit a new squad of 8 soldiers in Powered or Flying Armor (to shrug off "friendly" fire from missed shots), arm them up with a Laser Pistol for each, adding a Heavy Plasma to the 3 most accurate shooters for clearing Reapers (but only if Firing Accuracy is exceptionally high... otherwise they can be cleared with a few turns of concentrated small-arms laser fire).
I use the highest-TU soldier to scout below (just to have viewable area and not pure blackness... and then promptly return him/her to the upper level), and set everyone up in a center-facing circle around a single open lift-space... and let the Floaters come up into the meat-grinder on their own.
E = Empty space
L = Lift
S = Soldier w/ Laser
X = Solder w/ Laser + Plasma
The 3 Plasma soldiers have clear shots below to remove Reapers fro the Lift pad, while the full ring have centered fire on the single open Lift space that will inevitably be occupied by Floaters coming up to investigate.
Each soldier will get a chance to Reaction Fire until the Floater is incapacitated or killed. If it is incapacitated, a forced Snap Shot or two will surely clear the space for the next unlucky contestant.
Once all are dead, and no more come out to play, then it's just a matter of holstering weapons and dragging all of the remains and detritus up to the green exit tiles for extraction and aborting the mission.
If you feel adventurous, then you can explore the base for a random chance at a bit of free Elerium from the possible Power Supply(ies). (Always located in the SW corner of the second floor of the LARGE Base facility that is ringed by a cooridor and accessable only from a central door and single lift at the center... It's been outlined by other, more experienced, XCom Vets in another post.)
Depending on the placement of the entry-point, you can bag anywhere from 6 to 13+ aliens without any trouble. (If close-by to the Command Center, you can even expect the nearby Commander or Leaders to do most of the work for you with a Blaster Launcher round fired directly into the southern wall of the lower level (Alien-controlled Blaster Rounds have an aversion to going UP
Lifts...) Sure you get less overall experience gain, but the number of bagged aliens and alien hardware will go through the roof.** I HAVE had a single incident where a Leader got a Blaster Bomb up to my troops and wiped out the whole lot of them... I think he actually Berserk-fired up at an angle (missed shot) and hit one of the troops standing ON a Lift tile. But it was a single incident in a month-long string of raids.
Depending on the placement of the raiding party, scores range from mid-to-low hundreds (placed in far corner away from the Command Center, so only the outer sentries come calling) to 300+ (placed right next to the Command Center, with all dead but the single panicked Commander huddling in fear... his discarded Blaster Launcher sitting unfired a few yards away). With the number of gathered weapons (5+ Heavy, 1-2 Rifle, 0-3 Blaster, 0-1 Stun), clips (2 per Plasma, 3-4 Bombs per Blaster, 3 per Stun), grenades (1 for each Plasma-wielding alien), corpses (6-13 Floaters), and Elerium (usually 0, but have gotten 4 crystals equating to 200 units in one lucky run) moneymaking and monthly score is no longer a problem.
An average raid takes about 100 Turns (which FLY by, since most are just rapidly clicking "End Turn, End Turn, End Turn...", anyways) including rounds used to gather and pile up bodies, collect and clear weapons (all clips are removed added to the piles), and evacuate.
With the number of Reaction Fire shots, and the odd forced Snap Shot, experience will flow like a mountain stream in the springtime. And since a single Skyranger flying a distance from the North Pole to the Netherlands can make two raids per day.
By the time a month ends (Psi-Lab weeding schedule), the group of trainees are hardened soldiers, and only have their Psi-Strength to distinguish them from being heroes or history's forgotten has-beens. (8 Recruits, 2 Vets in each Psi-Lab cycle... raise the skill of Vets, while sifting through the others for acceptable Cydonia Troopers)