Transitioning from Hell to end game

How do people going about doing this ?

i have two chars currently finished hell around high 80s, able to farm most areas , so currently running cold fire sorc and fire lightning trap sorc, but i want to move into doing things like ubers, ancients and so on, i assume i am also using wrong classes here for this and dont mind making a new char to do so , but how do people transition or better yet find / farm the gear to be able to do so ?

Trying to do this in the most SSF way i can just to learn how to for most part even in the younger days of d2 i just spent my time farming dense areas and not thinking to much on getting things like torches and so on.

Is there a process to getting yourself ready for these kind of things or is it all just down to farm farm farm and luck ?

Lile u said sorc and trapsin are not really suited for ubers or ancients. You could do them with ur sin if you respec her to kick but we don't have access to Mosaic on ladder so it will be a bit trickier
If you want to play ssf then yes it's pretty much just endless farming and hoping you'll get lucky You'll have a much easier time getting the particular items you need by trading. There's not as much of a transition as much as it is just having a levelled char and working on filling out the checklist of items you need to do it

Usually the way to go was start with a paladin (hammerdin) as is very poweful, has few inmune enemies and can destroy every area with little to zero inverstment in gear. Then earn a fair amount of tokens and respect to smiter (another variant focused on staying alive and kill bosses).

I'd say warlock is still better than paladin to archive this.

alternatively, you can skip the ubers and just farm what your characters are good at: sorc is great at Key farming, meph / andy for instance. you can sell 3x3 keys for some decent value

It tends to be a gradual transition more than an intentional hard cut I would say.

As you play and as your level increases and access to gear expands, you're able to more reasonably (read: with acceptable clear speed) tackle more and higher content. Initially (online at least), that's moving from group runs (e.g. pug baals for xp) to solo farming. Then that farming expands in terms of zones/bosses you can reasonably cover. Then you grow into doing the same while terrorized. Perhaps within pug games for higher player counts. And for the most part, that's basically it.

Ancients, ubers and that jazz aren't really "the end game" so much as "an occasional end game side quest" imo as you typically won't keep yourself busy with those. If you really want to push yourself, you can run them with a sorc as well but that's just unnecessarily cumbersome and more gear-dependent than anything. That "side quest stuff" is far simpler to do with a dedicated character for exactly that content. A smiter tends to be the obvious and simplest example though switching your sin to Mosaic would equally suffice. In either case, you do want to tailor gear accordingly for the activity of choice (e.g. overstacking res) but for those dedicated characters, that's fairly easy to do without too much of an investment.