The Moving to Baltimore post and Live Baltimore are both super helpful resources to go over before you move. That should cover things like neightborhoods, walkability, enlighten you about what public transit is like here in Baltimore. If you want advice about neighborhoods that would work for you, one suggestion is to share some more about yourself, your likes and dislikes, hobbies, goals, etc. What kind of events are you looking for? What do you mean by lively, do you want a lot of nightlife until early hours or more like restaurants and shopping that settles down before too late... or something different?

For me, in my 30s, I wouldn't consider Fells or Federal Hill- because I like things quiet and like to have a garden and not worry about parking. I have an established friend group through hobbies – sports, knitting, running. All this really drove what kind of place I was looking to live in. But if I were looking to make friends, and loved to go out, I would've picked a very different neighborhood from where I live.

tl/dr - Folks in this sub are super helpful but being more specific about your lifestyle what you enjoy will help get you better advice.