Summary
One of the most popular campaigns fromDungeons & Dragonsis Curse of Strahd and with good reason. The aesthetic is great; it has one of the best official villains from D&D, the area is perfect for exploring, and the campaign can be quite hard. Since the players are free to take multiple routes, leveling them up can be confusing, depending on their trajectory.
Sure, you’re able to use experience points and just count their kills, but milestones also work well here. The book even has its recommendations for when to apply use milestones, which we’ll touch on, but it doesn’t give you enough specifics to reach level ten. So, when should you level your players up?

There will be spoilers for the campaign here.
Honorable Mention: Death House - For Levels One To Three
Curse of Strahd is a campaign that begins at level three and goes all the way to ten. That said, it’s normal for DMs to start at level one, so the book has a special side mission to start the game: the Death House.
Honestly, we have no notes here, as we highly recommend doing the Death House. It’s a great introduction, a good placeto introduce Strahdif you want to, and it gets the party to the appropriate level. It can be a bit too deadly for a low-level group, but it gets the job done.

9When Obtaining One Of The Key Items
One Level Per MacGuffin
The first thing the book recommends is to level them up when they get one of the following items: The Tome of Strahd, the Sunsword, and the Symbol of Ravenkind. With these, you get three milestones ready to go, and we also agree that it’s a good choice.
That said, we don’t recommend doing this if you put two of these items in the same place, since their location is technically random. Otherwise, you’ll end up giving them two levels right away.

If you put two milestones in the same place, such as having a milestone for completing Argynvostholt, but the Sunsword is also there, we recommend just doing one level up and using another milestone somewhere else. There are more milestone suggestions here than necessary to reach level ten, so have fun.
8Doing The Tarokka Reading
Just In Case
If you don’t want the game to get too dangerous, a good place to level the group up is after their encounter with Madam Eva. That happens relatively early, so using this will likely be the milestone that gets the party to level four.
This isn’t a violent encounter, so using this point as a milestone is just a way to ensure your players will be a bit stronger before fully exploring the dangers of Barovia.

7Retrieving The Bones
Saint Andral Thanks Ye
In Vallaki, there’s a whole story about the bones of St. Andral being stolen by the coffin maker, Henrik. You can level the players up once they safely return the bones to the church, thus saving the place from Strahd.
That said, retrieving the bones isn’t particularly difficult, depending on your players' current level. If you want to make this task harder, consider having Henrik deliver the bones to Morgantha, thus tying the Old Bonegrinder into this plot.

That said, if the adventurers go to the Old Bonegrinder first, consider leveling them up once they kill the hags instead of using the bones as milestone.
6Surviving Vallaki
Strahd Strikes
The book recommends many events in Vallaki, as it is the most developed town in Barovia. Which ones you’ll do is up to you, but we do recommend the attack on the church, which also ties in with the aforementioned bones.
Having a confrontation where Strahd appears is a good way to make things even more personal between him and the party, and leveling them up for surviving such an encounter is a nice reward.

5Saving Ireena
Down By The Lake
Most of the story revolves around saving Ireena Kolyana, who Strahd wants as his bride. Her story can go many different ways depending on what you want to do, what the players do during the campaign, and whether they succeed at protecting her or not.
Either way, one assured way to save her for good is to take her to Sergei in Krezk. If the players succeed, then you might as well level them up. This milestone is a hard one to trigger, though, so don’t count on it happening every time you run this adventure.

4Saving The Vineyard
Protect The Wine
This one is a bit more complicated. It’s technically a dungeon, but it’s not a particularly hard one. You should definitely reward the players here, but whether that reward will be a level-up or something else, that’s up to you.
If you choose not to level them up through the bones or the tarokka reading, this might be a good place to compensate for it because otherwise, the party might be too under-leveled for the missions ahead.

3Killing Lysaga
Or Retrieve The Gem
Baba Lysaga and her hut are among the hardest encounters here, so you could give your players something for the effort. It also ties in with the events of the vineyard, so if you didn’t level them up there, you could start this side quest to chase the hag and kill her.
Still, leveling them up in both places is also a good way to go. The vineyard is a good place for a level five group, while Lysaga’s swamp is level eight, so they can’t go from one to the other immediately, meaning the level-up helps in both places.

2Argynvostholt And The Amber Temple
Dungeon & Dungeon
Barovia has three big dungeons: Argynvostholt, the Amber Temple, andCastle Ravenloft.Since the Castle is mainly saved for the dinner and the end, we recommend having the characters already be level ten before going there so they can fight with everything they’ve got.
Thus, completing the house of the silver dragon and the cursed temple is worth two levels. They’re both high-level places, so using them during the second half of your campaign is good.

1Forming An Alliance With Strahd’s Enemy
The Enemy Of My Enemy
During the tarokka reading, you’ll assign an NPC to be Strahd’s enemy. Whoever you choose, the players will still have a mission to figure out who the card is talking about, and once that’s done, they still need to convince the person to join the fight. Once this recruitment quest is done, you could level them up.
As a bonus, these are our top recommendations for Strahd’s enemy:
Cards whose descriptions can be about more than one character is useful in case things don’t go as you expected and you lost the ally NPC, or if you want to swap to an NPC your players like more.