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Knowing all the rules is a solid foundation for your chess growth, as now you can calculate with more clarity.

To advance we need to cover the next base, you need to study the basic tactics, this can advantageusly be combined with studying the master games from the past, masters from the romantic era, this is any game played before the first official world chess championship match 1886,
the basic tactics are

• pin
• skewer
• discovered attack (or check)
• displacement
• removal of a defender
• fork
• Zwischenzug
• double-check (two pieces attacking the king)

These are very useful, and they can be combined to much bigger complexity.

Only move on when you really know the tactics in this section, master games is going to be a continous study from here on out.

Masters to study

Might be some of are a little after the 1st world championship match, but I still think you should study their games at this point.
Later you get to study masters of the later eras

Morphy

He dominated chess for a short while, he stopped playing when he had beaten most players soundly, but he still has some really great games.

Greco

To study the games of Greco is important, there is a lot of traps on display in these games so if you are booked up on Greco's games you can avoid a lot of those, also Greco dominated chess but a long time before Morphy.

Anderssen

Anderssen was a very big name, he lost catastrophically to Morphy but when Morphy stopped in chess probably Anderssen was one of the big names, he played some very nice combinations.

Staunton

A big name in British chess at the time, unfortunately not as strong as either Morphy or Anderssen he might have been a much more modern player but possibly he did not calculate as well as those.

Zukertort

He competed for the first world chess championship in a match against Steinitz, he actually was a student of Anderssen and surpassed his Teacher.

Steinitz

Steinitz won the first world chess championship match, he played some very nice attacking games, but possibly what is most known for is his discovery of small advantages, this is the foundation of development of a scientific approach to chess, as before you only had attacks and sacrifices to go by, but now you can evaluate a position by who has better pawn-structure or more active pieces, a safer king earlier this would not have been possibly, but thanks to Steinitz this happened.

Lasker

He became the world champion after beating Steinitz in 1894, a title he then kept until 1921!
He possibly did not have such a romantic style as all the other players I have posted here.

There are many other masters to study
La Bourdannais, MacDonald, Philidor and the list can go on, but if you start with studying the players I have listed you will find more players as the greats often played against each other, so if Steinitz played a lot of games with a particular player he might have been a great player as well.