Russia

Russia is a late-game superpower. Much like the Ottoman Empire to the south, it gets its first cores between 1444 and 1515 and maintains cores until the end of the game.

Overview
Russia is a very powerful country that doesn't have any serious local rivals in 1517. However, it'll eventually come into contact with stronger ones. Fighting the Polish-Lithuanian Commonwealth is a challenging task, and so are Sweden and the Ottomans. However, a skillful player can expand into these three powers one at a time and gradually eliminate them.

Early-game (1517 era)
The first task you should do is, unlike most countries, shift towards conquest and expansion early as you have a large army base and can easily take down any neighbouring countries (except for Lithuania and Sweden). Defeat Ryazan first as it is an OPM (One Province Minor) and could be taken down easily by your whole reserve, then focus hoarding power to expand eastwards by researching colonial tech. Later on, expanding into Sweden and Crimea is also prudent, as these areas gives you a larger coastline for a bigger navy, which Russia severely lacks at the start.

Mid-game (1648 era)
As you defeated Sweden and took coastal lands. Amass your army&navy to defeat the PLC (Polish-Lithuanian Commonwealth). It's recommended that you have a strong/loyal ally to help you defeat PLC such as Austria, Brandenburg, or even Prussia (much like OTL (On IRL timeline)) even though you could defeat them by your own. But, do not annex more than 80% of their lands as you need to worry about your overextension now because of your large empire. So you need to gradually annex lands from it until PLC isn't a major power threat anymore.