One of my favorite authors is Mercedes Lackey. Her worlds of Valdemar and the alternate history of the Elemental Masters are among my favorite haunts. Valdemar is sword and sorcery medieval times, which makes it sound much more bland then it is. The alternate history of the Elemental Masters is England in various time periods but mostly Victorian running up to the First World War.
To start you off at the beginning of the Valdemar series, book wise not chronologically, is with the Arrows series(DB 32573,39678,39710) The series follows Talia from a very backwoods life in Valdemar, through her Choosing and training to taking up one of the most valued positions in the kingdom. On the way you meet a few other characters who go on to have their own books or even series.
This is the best introduction, in my view, as it is the first book Mercedes wrote in the universe. And she stays pretty true to her beginnings. There is some retconning, the most egregious of which how many times she has someone create the same sport the main characters are inevitably interested in, but mostly she has made her timeline and is sticking to it.
To go into the Elemental masters series is a bit different. There are two separate timelines, I think. One is of the Elemental masters in truth, those who control the elements of fire, water, earth and wind. These have characters who show up in each others books and there is a central organizing force of a Council of Masters. These books are based on fairy tales but with rather large changes.
The second timeline takes place in that world’s past. This guess is based on that one of the secondary characters is only in his 30’s in this time, but is called the Old Man in the first timeline. This timeline, I call it the second because Mercedes wrote the first book in this timeline after writing three in the first timeline, focus on Sarah and Nan(DB 67296) who are mediumistic and telepathic respectively.
Both these series are excellent and I highly recommend them. They are YA novels so you should be aware of that but they are good writing and just a cool magic system in both.