For Ultima IV you need to take lots and lots and lots of notes. Thankfully that's very easy nowadays since DOSBox has an inbuilt screencapper. So take screenshots of everything NPCs say. Figuring out the puzzle and becoming the Avatar of Virtue is what makes U4 worth playing.
But it might be better to start with a smaller and simpler game. Wizardry 1 is a good starting point. Play cautiously, and return frequently to town to heal and replenish spell points. And make sure you make a map. There are several programs you can use for that.
I do not think that Ultima IV or Wizardry 1 are good games to play at all.
There are 3 types of famous old game:
1. Games witch were thresholds of the genre, great for their times, but nothing special today. Those games introduced some new things which show the direction of cRPG evolution but later titles did everything in a better way. Ultima IV and Wizardry are, for me, games of this type.
Why Ultima IV was special? Because it introduce deep story and lore to the cRPGs formula. Previos titles were mostly about hacking through dungeons, gaining experience and collecting equipment. Ultima IV added detailed world with history and a story more complicated than: kill evil wizard. It was a blast of those ancient era, but now… Everything Ultima IV did Fallout did better. It is no reason to play it today (other then love to the Britain universe or historical lesson). The same thing is with Wizardry 1. Its contribution to the genre was introducing deep character system and hard tactical battles – but newer games do the same without atrocious graphic and stupidly hard design.
2. Games that are Neanderthals of the genre, the blind paths of the evolution. This games constructed cRPG around ideas, which will not be followed. Sometimes it is a pity. This games are not good
per se but could be interesting if you value some specific ideas. For example: Robinson's Requiem; super realistic simulator of life in wilderness. You have to hunt for food, manage your health (it is very easy to die because of disease) etc. The game is pain to play, but could be interesting.
3. Games that are universally good and always worth to play. They mastered some aspects of cRPG design and, despite of technical limitations, do some things better then even the newest titles. For me, as I said, the best examples of such games are M&M 3-5. You can also count Ultima 7 – the game with a massive open-world exploration, with great interactivity (dialogues, manipulating objects), with living world (NPC schedules, rain, wild animals), lots of secrets and cool stuff (flying carpet…).
As a supplement to my tale I would recommend You some modern conversions of old titles:
-Good way to play Ultima 7:
http://exult.sourceforge.net/
-Ultima 5 on Dungeon Siege engine:
https://www.u5lazarus.com/
-the same with Ultima 6:
http://u6project.com/
-Realms of Arkania 1 and 2 had commercial adaptations (I haven’t play so I know nothing about quality):
https://store.steampowered.com/app/237550/Realms_of_Arkania_Blade_of_Destiny/?l=polish
and
https://store.steampowered.com/app/288860/Realms_of_Arkania_Star_Trail/
I also recommend to start from the games which are old-school in spirit but not very old. As I mentioned: Might and Magic X Legacy, Legend of Grimrock, Arx Fatalis, Wizards and Warriors.