Tips:
Surviving the first small UFO waves (big spoiler):
Spoiler
There are three unlimited-range, pretty fast UFOs that abduct CNs - which might be unexpected (they usually don't do that).
You can't shoot them down in time, at least not initially, but abducted CNs will be back after 20 seconds like usual, so losing all CNs isn't defeat.
You can mitigate this:
Spoiler
Deploy just one or two CNs. Deploy the third one only when you see another CN abducted, so your packet network remains supplied.
Dealing with the masses of incoming UFOs:
Spoiler
Don't worry too much about getting your units abducted. With enough energy, you can rebuild faster than they can abduct.
(Having to rebuild in all kinds of spots is kinda annoying though, but you have to rebuild to keep your energy up.)
Being sustainable:
Spoiler
Do a regular check on your front and see if too much was abducted.
It's okay to lose some beams, but once they start eating into your energy production, you need to put a stop to that.
Conserving energy:
Spoiler
Don't bother killing the UFOs. It's cheaper to shoot them down when they revive.
UFOs respawn in groups of four, so if you kill three UFOs and keep the fourth one grounded, that's the cheapest option; however, since UFOs tend to change position after reviving and will fall into a chasm eventually, you can't really control that, and keeping track of UFO groups is going to be too much work to be worth the bother. Just make sure there are enough beams around to shoot down any reviving and incombing UFOs.
Ore and AC:
Spoiler
Useless initially; your starting island is not threatened by creeper.
Later just use AC as you would normally.