It is very important to learn ASL from credible, trustworthy people. Oftentimes, that means learning from someone who is Deaf.
If you are ever looking up a sign online, please use the "Check 3" method: the same sign should be verified across 3 different platforms. Regional signs do exist, so it is important to make sure you see the sign being used consistently.
Please also be aware that American Sign Language is primarily used in North America. ASL is NOT a universal language. Different sign languages DO EXIST! For example, the manual alphabet in ASL is not the same as it is in other countries, such as Ireland (ISL) or England (BSL). The same gesture in ASL and BSL can mean two entirely different things, which is why credible sources are crucial.
I would be more than happy to help you find resources to fit your specific needs. Please reach out if you ever need help or have any questions!
Dictionaries:
https://www.handspeak.com/word/
https://www.lifeprint.com/search.htm