Every block you move in the Nether is eight blocks in the Overworld. That single ratio is why almost every established world ends up with a Nether transport network.
The maths in practice
A base 4,000 blocks from spawn is a long, dull walk. In the Nether it is 500 blocks — a couple of minutes on an ice road. A 10,000 block journey becomes 1,250. The further apart your bases, the more the Nether saves you.
Building the link
Stand at your Overworld portal and note the coordinates. Divide X and Z by eight — or paste them into the nether portal calculator — and that is where the matching Nether portal belongs. Build it there yourself rather than letting the game generate one, then tunnel between your Nether portals.
Making the tunnel fast
A plain two-block-high tunnel works, but blue ice with a boat is dramatically faster and costs nothing to run. Packed ice is the cheaper alternative. Light the tunnel well, wall it off from the surrounding terrain, and you remove both mob spawns and the risk of a ghast fireball catching you mid-run.
Dig at Y level 128 and above if you want to avoid lava entirely, or stay low and just never dig straight into an unchecked wall.
Two things that go wrong
Portals stealing each other is the classic problem: two Overworld portals a few hundred blocks apart can land close enough together in the Nether to share an exit. Build both sides at exact calculated positions and it stops happening.
The other is forgetting fire resistance. A single ghast hit near a lava lake ends a trip quickly, and the Nether does not forgive falls into lava the way the Overworld forgives most mistakes.