Hi I recently bought D2R having never played D2. I have a level 46 sorceress with, I assume, a problem, she is too fragile. On normal difficulty it goes pretty fast but on nightmare difficulty it is unplayable the damage is ok but it is too fragile and dies before I can cure it. It has a defense of 432, I tried to invest points on chilling armor by increasing the defense up to more than 650 but it is as if I had not done it: as it was before (it cost me 5 skill points). As if that weren’t enough I have found much, much stronger players online at the same level. What do you advise me to do at this point? Normal difficulty is fine but there is very little experience there and nothing decent can be found, I would like to go to nightmare but I can’t, is the defense too low? because the damage she does is acceptable. What to do? Thank you
Oh! Leveling enchantress is a horror!
Level 80+ enchantress could be good, especially with maxed telekinesis and level 40 energy shield, but middle levels are always a huge struggle.
I suppose, the main problem is your low resistances, not defence.
You could try some bow or crossbow with explosive arrows: raven claw, kuko shakaku or demon machine.
Also, a good, geared mercenary will help a lot.
do you advise me to change class?
mercenaries go down with nothing
Strength: Enough to use your gear
Dex: Same (most of the time nothing here)
Vit: the rest
Energy: nothing
Armor doesnt really count on Sorc, ignore that. Try to get some resistances for NM/Hell. With negative resistances its most of the time a oneshot, no fun to play like this. How does your skills look like? In which tree did you invest your points?
Also, get a Act 2 Nightmare Merc, if you are a fire sorc with holy freeze. Try to build the runeword “insight” for him, should fix any manaproblems.
almost everything in fire bolt and fire ball
the mercenary of act 2 dies immediately
any advice to increase the resistances?
Not optimal, but for the beginning you can go on with this, try to spend some points into meteor. But be aware, in hell many mobs are fire immune. Maybe its better to respec in a Frozen Orb/Fire Ball spec or something you like. But definitaly in a 2-Element Spec.
Well, he needs to be geared up as well. Insight as weapon, Duriels Shell, Shaftstopper etc. as Armor and f.e. Tal Rashas Helm for Life Leech. Or Vampire Gaze.
Cheap things for the beginning are Runewords like NefLum in Armor, RalOrtTal in Shield.
sorceress is a fast glass cannon, if you fins that not to your liking, one alternative could be the druid or the summon necro, they both put up meat shields in front of them
Give some good items to him. Attack speed, life leech+damage are the best stats.
You made a missleading title. It is not an enchantress, it is a regular fire sorceress. Come back, when you gonna make a melee enchantress. She is really too fragile at mid levels and hard to level up. Regular sorceress is very easy until hell difficulty. You need no special hints here. Just play and use items you found. If totally screwed up stats, create a new character and try again from the scratch.
how do i make a melee enchantress?
To make an ENCHANTress, you put skill points to ENCHANT, fire mastery and warmth.
There are plenty options to achieve survivability, e.g. full energy shield build. I’m not gonna write a guide here, but if you have some specific questions, feel free to ask.
if the problem is really the resistances (and it probably is since I have a -11% fire resistance) with the smoke runeword I should be fine, +50 to all resistances should be enough, right? because such a weakness cannot be explained with 650 defense. I wonder why to make such a problematic class and if they will fix it in the future
Squishy sorceress is debatable. She is a bit of a glass canon with bit lower HP overall, but in return has options to kill from afar, hit all opponents and standard fastest movement and flight options in game.
One thing you have to understand in this game though is how defence work. It does not diminish damage, but the chance you get hit. same with a shield. With higher defence you will get hit less often, but each hit will be still just as hard. For sorceress with lower hp that means getting hit can be quite bad especially if also low elemental resistances (those do lessen the damage if high), on other hand she has the skills and options that make it possible not to get hit so much or at all.
Try out other classes and builds especially in Hell that have to get close and get hit much more often even with 2K defence. 
There is a reason why almost every top build for every class is a build that does damage from a distance unless you have OP items for the class.