1444-1454
Ally Denmark.
DOW Novgorod. Grab as much land as possible and release Finland (and make vassal: marriage, alliance and a bit of gold are enough to diplo-vassalize).
Ally Poland (after their PU with Lithuania). You want Lithuania in a PU to run wild in the first two decades.
DOW Tver/Ryazan. Vassalize Ryazan and annex Tver.
DOW Livonia when at war with Poland (they are allied to Teutons who always get attacked by Poland after the PU with Lithuania). Vassalize after they have made peace with Poland (or you'll be dragged in the war against Poland). Turn Riga to Orthodox (they will join Livonia in this war). Take a single province that allows fabricating a claim on Riga, then sell back to Livonia.
All the above mean having 8 diplo relations (POL-DEN as allies, Ryazan, Pskov, Yaroslav, Finland, Perm, Livonia as vassals)! Don't worry. You have a 5 diplo heir waiting. You will be making at least 1 diplo point per month.
1454-1464
Start annexing Yaroslav and Perm (to open the way for Siberia) to reduce diplo relations to 6.
Finish off NOV in final war and release as vassal (but make sure you have fabricated a claim on Sweden before releasing).
Invade and annex Riga.
1464 - onwards
Around 1484 you should have also annexed Novgorod and either Pskov or Ryazan to further reduce diplo relations.
Usually the Golden Horde are the first target to vassalize. They lose provinces to Crimea and can usually vassalize in one war. Make sure to take provinces to fabricate claims on Crimea and Nogai. Then sell them back.
Attack Nogai to drag Crimea in the war (your next target). Return cores to Golden Horde and take enough provinces to vassalize in next war. Vassalize Crimea before the Ottomans discover you (to avoid them joining a coalition).
Then Kazan, then Nogai (or the other way round depending on alliances).
Be patient with Denmark-Sweden. Eventually they will get bogged down in a bad war or Denmark will lose the PU due to bad prestige. Invade to return cores to Finland. End the alliance/marriage with Denmark to further reduce diplo relations.
Be patient with Poland-Lithuania. They always get involved in a bad war. DOW Lithuania and take provinces/release nations. After the end of the war, Poland will be happy to once again become your ally

Keep an eye on their prestige.
WESTERNIZE, around 1510. You'll be saving tons of Points (esp. once you've researched Russia's last NI). Now it is so easy, there is no reason why you shouldn't.
For ideas I usually go Expansion (take the first idea for the colonist, then rush to level 7 to open new group, then all other ideas for the CB), then Offensive (or other military idea), then Religion.
Then, the world!