Base Farming

Base Farming involves finding an Alien Base and then constructing a base on top of it. Once you have it set up with a radar, stores, men and a Skyranger, you may begin farming off the base's supply drop offs. Between 150 to 900 Elerium is worth the -150 points you'll get at the end of the month. And the best part is if you get bored of it then you just attack the base and then dismantle yours so it can be built over another one, and you may have up to seven of these if you do not have Research/Manufacturing/intercept/Radar bases.

Things you'll need

A Skyranger
However many soldiers you wish to train
Laser or Plasma Weapons
Stores for loot
A Hyper-wave Decoder (If you can’t get it yet, then use a Large Radar but it does not work as well)
Bring Grenades or High Explosives as the Supply Ships top floor has a maze of corridors on the south end of the ship. Also the leader outside the control room sometimes reacts and shoots you if it is facing that direction. (For another fix to this you could always shoot through the wall to the bridge.)

Rules of Farming

Alien Race Consideration

Obviously don't go for Ethereals as they have Psionics, which can get really annoying and drag out the battle.
Only go for Sectoids if you are psionically trained, need a leader for psionics or just want bravery training
Don't go for Mutons if you are using Laser Weaponry is not recommend as lasers are weak against their armour. (If you have Plasma go ahead)
So that leaves Snakemen and Floaters. Snakemen are okay if you are going after the Supply Ships, but bases’ have nasty little Chryssalids. (If your men have good reactions and Plasma Weapons then this works fine)
So for Bases alone, Floaters are Probably best.
But for Supply Ships, Mutons if you have heavy Plasmas, Floaters because they are weak little things and Snakemen because they do not have Chryssalids with them.
Mutons also make great PSI improving dummies. Muton bases and Supply Ships are basically just sat their with a sign saying come train here. Train PSI on Supply Ships, and train PSI and Reactions in bases.

Terrain Consideration

Bases that are East of Europe and West of New Zealand, and in-between the poles to ensure you have a daytime Mission, due to the fact that Alien Supply missions always occur at the same time.
- Learn the types of terrain so that you can make a educated guess on where to farm from, especially if you have multiple bases from.

Ideas from Zarn

The best choices are flat and level deserts and arctic terrain. Farms are acceptable, though you'll have to deal with the barns and stables. Jungles, forests and mountains are to be avoided.
- Know the different appearance of sub types of terrains. Deserts may be flat or hilly. Arctic terrain may be solid or puddly:

- Unless you have flying suits, the puddly ice may present serious obstacles.
- In farm terrain, remember that opening unexpected holes in buildings can be advantageous, and remember to check orchards thoroughly. Alternatively, you may choose to flatten the entire battlefield. If this is your choice you will gain some extra cash from demolishing the 1st level of buildings before the 2nd, as this will prevent the eradication of items that fell from the 2nd floor.

Other Recommendations

If you are looking to train a few people in particular, in one aspect or another, then pick the appropriate base and alien type and then only stock your Skyranger with those soldiers in order to train their particular skill.
Only go after Supply Ships if you have a Hyper-wave Decoder, and it is probably more worth it to just destroy the Alien Bases over trying to farm a base that is being restocked by ships that you can not see.

Perfectionist

If you hate casualties then just assault the first floor of the UFO, shoot the Power Sources grab the Elerium and then run back to safety within the Skyranger, (Grab whatever else you desire), and then abort the mission. And then if you get the chance, shoot the UFO out of the sky and raid it again.

With the UFOextender Mod

Due to a small bug in the Initial Alien Bases part of the mod, around every four times you place your base, you will end up with alien bases 2, 3, and 4 on top. So grab a Skyranger an orbit around for a little while until you detect them. The morale of the story, place your base on your favourite terrain in the regions specified above.

Images Demonstrating this version of Base Farming

Step 1 of base farming. Find an alien base
Step 2 of base farming. Make another base on top of the alien base
Step 3 of base farming. Build a the facilities needed. Defend-ability doesn't matter as you are just attacking landed UFOs
Step 4 of base farming. Buy and name (Optional) your soldiers, bring in Supplies such as Plasma and Laser and then happy hunting