Seven Roads To Hell

No one goes to hell by committing sin in the abstract, sin in general. Our character traits, talents and dispositions, our experiences — everything about us points out to us a particular road to hell — one of the seven that are called the capital sins. For us, this or that particular one is the fastest and easiest because of who we are, what we are, where we find ourselves. And the road sign will read either pride, covetousness, lust, anger, gluttony, envy or sloth.

The seven capital sins are called capital because they are the sins of primary importance and inevitably spawn a whole litter of other sins. Pride leads to boasting, ostentation, hypocrisy; envy is followed by hatred, discord, a restless quest for riches and honors, and constant turmoil of soul. The slothful man is idle, aimless, neglects his spiritual duties and the obligations of his state in life. And so on for the other capital sins. They all lead to other sins. They’re all roads to hell. Most important, we must find out whether we’re traveling one of these roads.
Where souls go after death
Aquinas uses an analogy of buoyancy:

And since a place is assigned to souls in keeping with their reward or punishment, as soon as the soul is set free from the body it is either plunged into hell or soars to heaven, unless it be held back by some debt, for which its flight must needs be delayed until the soul is first of all cleansed. … Sometimes venial sin, though needing first of all to be cleansed, is an obstacle to the receiving of the reward; the result being that the reward is delayed. [10]

— St Thomas Aquinas, Summa theologiae Suppl. Q69 A2
As self-exclusion
The Catechism of the Catholic Church which, when published in 1992, Pope John Paul II declared to be “a sure norm for teaching the faith”,[43] defines hell as a freely chosen consequence of refusing to love God:

We cannot be united with God unless we freely choose to love him. But we cannot love God if we sin gravely against him, against our neighbor or against ourselves: “He who does not love remains in death. Anyone who hates his brother is a murderer, and you know that no murderer has eternal life abiding in him.” Our Lord warns us that we shall be separated from him if we fail to meet the serious needs of the poor and the little ones who are his brethren. To die in mortal sin without repenting and accepting God’s merciful love means remaining separated from him for ever by our own free choice. This state of definitive self-exclusion from communion with God and the blessed is called “hell.” Jesus often speaks of “Gehenna” of “the unquenchable fire” reserved for those who to the end of their lives refuse to believe and be converted, where both soul and body can be lost. Jesus solemnly proclaims that he “will send his angels, and they will gather… all evil doers, and throw them into the furnace of fire,” and that he will pronounce the condemnation: “Depart from me, you cursed, into the eternal fire!” The teaching of the Church affirms the existence of hell and its eternity. Immediately after death the souls of those who die in a state of mortal sin descend into hell, which is described (in quotes) as “eternal fire.”