D2R Newb returning - Nightmare HC Firetrap

Hi Everyone. I haven't played D2R since launch, where I got my non-ladder warcry barbarian to level 75 in hell solo before I burnt out in act 5.

I came back last week with my RL friend and i started playing an easy beginner guide for a class I've never played, the assassin.
I am using a wowhead beginner guide this one: https://www.wowhead.com/diablo-2/guide/ ... strategies

This basically walks me through what to do 1-40.

I want to dive a bit deeper but I tend to get overwhelmed and frustrated with the amount of choice in runewords and builds. I tend to like the game of D2R but I am not huge on theorycrafting or knowing "when" to switch a build because I am fairly casual. Is there a good set of goals for me to prepare for level 40 when this guide recommends respeccing? The only plan I have right now is to farm for Spirit runes and then do the cow level to try to get a crystal 3 socket sword that I can add socket to. Beyond that using the ancients pledge shield is all I've really planned for. I have had fun with this fire trapper but know it falls off because of resistance to fire.

Any tips/tricks and uniques/item merchant farming i should do will be greatly appreciated. I am currently running Stealth/Leaf and no other rune words, and have a teleportation staff i grabbed from merchant for 16k.

This is in hardcore mode at nightmare difficulty act 1 currently.

Spirit, Lore, Ancient's Pledge and Insight (for Merc) have runes easy to farm on

The Countess nightmare

(you can farm a Spirit

Crystal Sword base on Normal Cows )