The nodes represent places where things increase and decrease. Try to look at it on a practical level rather than a rainbow-butterfly level — it makes it easier to digest.
As a rule, the north node (NN) will typically give increase to whatever house it is in. The south node (SN) will give decrease to whatever house it is in — good or ill.
Also, the NN is exalted in Gemini and the SN is exalted in Sagittarius (according to Ptolemy). I have no idea why.
Let’s take mine for example. My NN is in the 1st in Aquarius. So it increases 1st house stuff. Too bad it’s not conjunct any good planets, it would increase their good. Anything close to the NN is increased, whether good or ill.
And my SN is in my 7th house, conjunct Mars by a wide 7-8 degrees, but still conjunct. SN will probably corrupt/reduce some 7th house stuff but seeing as my 7th house is ruled exclusively by the Sun I’ve been hoping he can stave off some of its badness.
Another cool thing. NN increases stuff, SN decreases stuff. So let’s say NN is conjunct Mars, it will make his...nastiness far more potent. But if it was conjunct Jupiter it would make his goodness more potent.
Likewise, the SN reduces. So it being conjunct a good planet reduces its goodness (depending on the distance. Ben Dykes claims the further away it is the less effect it should have, but it’ll still affect whatever house it is in, same goes for the NN). For me, my angular Mars is considered conjunct the SN, which actually reduces his nastiness.
So basically the NN is benefic with benefics and malefic with malefics, while the SN is malefic with the benefics and benefic with the malefics.