As an evil the game can be divided into 3 phases. These phases are critical to consistently winning as the evils.
Phase 1: Invest hunting/Finding converts
Unseen:
The unseen cares a lot more about who they convert than cult does. The classes you want to find are in order: Sheriff, Princess and Observer. These classes are critical to getting the info you need. After getting finding one of these you sacrifice one of your first converts and convert the invest class.
Cult:
For the cult things are much easier. You want to get as meany seekers as possible to speed up investigations latter.
Regardless of faction you need the invest roles for Phase 2:
Phase 2: Prince/Priest hunting
Unseen:
Now that you have invest classes you need to find the unconvertable classes ASAP. Once you find them you need to kill them at all costs. You need the invest classes so that you can find them BEFORE they out themselves. If the BD knows who the Prince and Priest is then things are much harder for you as you would first need to find and kill the protective classes. 2 for 1 is useful for this but nightshade is not. Try to kill the Priest before the Prince because that way you can take them both out without the BD ever knowing who they were.
Cult:
As the cult you can often investigate quickly if you did well in phase 1 getting the Types out of 2 or 3 people each night plus day claims. Remember to replace spent Seekers as needed. Getting one ritualist is recommended to help take out the priest but once you get one you need to kill any support you can find. Once the priest is dead and hopefully the CW you can focus on finding killer classes and therefor the prince.
Phase 3: Berserk mode
Unseen:
If you have made it this far then you probably already have majority. If you don’t then have one of your non-MM call someone out to force a misslynch and secure the win. If there are still many players left then you might get a few more converts out. Remember: If your not the MM then your job is not to seem BD but to make others seem Unseen. Be as aggressive as you can as each sacrifice means another convert. Just remember to lay low for a day afterwords while convert is on cooldown. The class you will want to have to close out the game is the illusionist. Preferably an evil king too, the illusionist is excellent at causing misslynches as you can accuse people in a way that is credible without even outing who you are.
Cult:
Late game can be a problem for the Cult. Unlike the unseen there are likely still many players left to kill and are going to have to cause many more misslynches than the unseen do. Just try to find and convert the nobles and psychic. If you can get a Cult king then you have basically already won. The apostle is excellent because you can trick the remaining BD invest classes to preform the misslynches themselves and giving you an extra lynch on them. Remember that like the unseen, getting your own members killed is almost as important as killing BD.
Something to keep in mind are that
A: getting the prince to lose his executes is almost as good as killing him.
B: As unseen the MM is the ONLY unseen that actually should put looking BD over killing BD as without the MM you can’t be as reckless.
C: As Cult you need to keep the prince away from the Cult leader at all costs. If the prince keeps the CL in jail then the Cult can’t kill or convert rendering you without means of attack while they can investigate all they want.
For details on how to best cause misslynches read this thread: https://forum.imperium42.com/t/the-power-of-blatant-lies/7545/13
For interesting ways to counter-play Prince read this thread: https://forum.imperium42.com/t/ways-to-fake-claim-prince-needs-testing-feedback/3065
