Good and Evil is a big topic, too big to cover in a small simple blogpost, but I'd like to write a few words about it.
Let's start with some basics, Asatru does not have two extremes of good and evil, or a heaven and hell.
The land of the dead is known as Hel or Helhem, but isn't in any way bad or evil.
It's said that thiefs and oathbreakers go to bad places however, and probably the worst is Nifelhem, the world of ice, which is below the world of Hel.
In Asatru we don't believe that there is any single being responsible for bringing good or bad, each person is responsible for their own actions.
Dying means going to another world, another place, which one? That depends on what you want, what you are like as a person, what choices you make, and of course it may help if you're friends with the god who presides where you would like to go.
Good faith doesn't save you from your actions however, you can't blame other people, gods, or any other being for things you decide to do.
Let's take an example, Loki at one point tricked Hödur to shoot his brother Balder with an arrow made out mistletoe, which killed the otherwise immortal Balder.
Who's to blame? Both Loki and Hödur, Loki because he tricked Höder, and Höder for blindly putting his faith in Loki without finding out for certain first if there was any issue with using the arrow made of mistle-toe.
Odin and Rindr gave birth to a son they namem Vali, who was born in the sole purpose of revenging the death of Balder by killing Höder.
There's more to the story of course, Hela (Or Hel, the goddess of the area Hel) promised that she would let Balder go back, if all beings in the world wept for him, and everything did, except for one giantess, she would not cry for Balder.
As it turns out, the "giantess" was actually Loki after having shapeshifted so as to keep Balder in Hels domain (For which he was severely punished by the Aesirs.)
How can we take that and use as a lesson so as not to end up as Höder?
Don't put your blind faith into anything, always do your best to know everything you need to know before putting it into action.
Is Loki evil? Not, he may be a trickster but he is not evil, no one is pure evil or pure good, no matter how much we would like to believe so.
We are all responsible for our own actions and our own words, never will an Asatru blame anyone else for their own actions, as that would be a cowards thing to do.
It's not hard to be "good" in Asatru.
There are a few different "codifications" of Asatru texts, the common ones are the Nine Noble Virtues (Codified by the Odinic Rite)
Courage
Truth
Honour Fidelity Discipline Hospitality Self Reliance Industriousness Perseverance
There is also the Asatru Folk Assembly version:
Strength is better than weakness
Courage is better than cowardice Joy is better than guilt Honour is better than dishonour Freedom is better than slavery Kinship is better than alienation Realism is better than dogmatism Vigor is better than lifelessness Ancestry is better than universalism
And of course there's also the Nine Charges (Also by the Odinic Rite)
To maintain candour and fidelity in love and devotion to the tried friend: though he strike me I will do him no scathe.
Never to make wrongsome oath: for great and grim is the reward for the breaking of plighted troth. To deal not hardly with the humble and the lowly. To remember the respect that is due to great age. To suffer no evil to go unremedied and to fight against the enemies of Faith, Folk and Family: my foes I will fight in the field, nor will I stay to be burnt in my house. To succour the friendless but to put no faith in the pledged word of a stranger people. If I hear the fool's word of a drunken man I will strive not: for many a grief and the very death groweth from out such things. To give kind heed to dead people: straw dead, sea dead or sword dead. To abide by the enactments of lawful authority and to bear with courage the decrees of the Norns.
These simple codifications will help you in your daily life to live according to the teachings of Asatru.
(A codification is basically a summary, in this case they're summaries of how we're taught to live and be, according to the various texts, poems, and lore in Asatru.)