for pirating?
1. search for games that interest you on vndb.org
1.5 you can find some otomes here too (most of them under 'no sexual content' tag); you can also take your chances and request something in the game request section here if you can't find some game anywhere else
2. sometimes the game is free and there will be a download link under releases on vndb
3. otherwise, search the internet for the game that caught your interest (piracy subreddit's megathread has a list of more trusted sites you can check)
3.5 avoid igg games if you can find the game elsewhere
4. always use protection; adblock/ublock in the browser for getting rid of malicious or aggressive ads on some piracy sites, check downloaded files with an antivirus or virustotal, look into running games through sandboxie (easy to set up and works well even on a low-end machine), virtual machine or on a secondary computer/laptop where you don't keep any important or sensitive files
5. some places i'd check: japanese games - anime sharing site, steam games - cs rin ru site; ryuugames has some otomes too
5.5 for cs rin ru, games may be provided as a copy of steam installation of the game and require goldberg steam emulator (easy to use)
for buying legally?
1. search for games that interest you on vndb.org
1.5 or join sites and communities dedicated to otome games
2. use provided link to official sources for buying the games legally (or downloading legally if they're free)