Stop. You are going to Hell. Turn around and go back. Reb Israel Salanter

I have given Hell a lot of consideration, and I would like to divide the topic into two parts. One part is "What actually gets a person out of Hell?" and the other is "What is sin?"  

First I want to give my perspective and then mention other points of view.

My own perspective on this issue really came to me one Rosh Hashanah at the Mir yeshiva when I was already married. During Musaf during חזרת הש''ץ (repeating of the prayers) I spent learning the אור ישראל Light of Israel of a disciple of Reb Israel Salanter, Isaac Blazer.  
That book is really a collection of several books but the one I opened up to dealt with the difficulty of getting out of Hell.[I have zero sefarim with me so I can not look it up to tell you which book it is. I vaguely recall that it is the first section.] His point is simple. It is hard to get out of Hell. He brings lots of proofs from the Talmud. Thus, even if one is thinking he keeps the entire Torah properly, (or thinks he has some other guarantee), in all likelihood he or she is deciding based on lack of evidence. 
To a lesser degree you can see this same in the books of the Chafetz Chaim, Reb Israel Meir HaCohen.

What bears on this issue in terms of an answer I want to bring the Reshash (Shalom Sharabi) and the Rambam.

The Reshash in Nahar Shalom נהר שלום says the soul is the character traits. Mitzvot are only the clothing of the soul. Learning Torah is nourishment of the soul. Thus a sin one can repent on. Also lack of Torah. But a lack of a good character trait is a basic limb of the soul that is missing. On that little can help. מעוות לא יתוקן
Proverbs "What is crooked can not be made straight." [The Chafetz Chaim says the same in שמירת הלשון.]

The Rambam says in Mishne Torah that one's portion in the next world depends on גודל המעשים וגודל החכמה deeds and wisdom.
[Thus what matters in the long run is not one's standing in the superorganism nor one's social group. Nor commitment to religious or political movements.]

[During the Middle Ages the issue of Hell was in the forefront of most people's mind. See Dante for example. Dante for me was גירסה דינקותא the learning of my youth. I had it with me all the time in high school. One thing you see in Dante is this same opinion expressed by the Reshash--that Hell depends on character traits. Each circle of Hell is for one particular character trait. I forget the order. I think the top is for excess desire, then anger, greed, lying, stealing, and being traitorous to people that trust one.

The christian perspective also relates to the issue of how not to go to  Hell and instead go to the Garden of Eden.[called salvation]. (Soteriology). To the Catholic baptism is a sine qua none for salvation. But it apparently is not sufficient. One can wreak it up as we see in Dante lots of people in Hell even after being baptized including a pope.  [That is there are things  that take care of Purgatory. But that is not baptism. But baptism does not save from Hell proper if one does any of the deadly sins like lying etc.]

  Protestants  don't believe in that but rather say faith alone saves, but good character is an epi-phenomenon of being in fact saved.
In any case, there is also the basic fact of salvation and good character [human decency] as being closely tied. [There is some degree of tension here. Catholic are trying to have their pie and eat it too. They want sin to be forgiven by baptism but then to still need repentance. And Protestants want to have no sin after one says a few words about faith. This trivializes sin.]

Now there is another subject of what is sin. Protestants mainly want to define this without reference to the Bible. This  has some justification since they are looking for what you would call wholesome living  along with kindness. That is the exact same things I was discussing above about having good character. Still the ignoring completely the laws of the Torah and making up their own set of what is called sin is disturbing to me and apparently also to Peter and James in The Recognitions of Clement. [
Baur was the first to point  out, and his followers in the Tübingen school elaborated his views into the theory that Simon Magus is simply the legendary symbol for Paul. The remarkable similarity of the doctrinal points at issue in both the Petro-Simonian and Petro-Pauline controversies cannot be denied, and the scholarly reputation of the Tübingen school is such to make this probable..] Apparently Paul came up with this doctrine and as we see in the first Corinthians his followers took him quiet literally which left him aghast and caused him to backpedal.

To make a long story short what my approach is is mainly that of Reb Israel Salanter in the sense that I accept this idea that midot is the main and primary thing. However I also can see the idea that midot is an epiphenomenon of some internal state of the soul. This was note by the Chazon Ish --that midot do not come differentiated. One is either a good and decent person and that is that or not. Kant noticed the same thing and he called it by some name that I forget. The idea is that one is either radically good or radically bad based on one thing alone--the acceptance of the moral law.