Since no one else was answering.

1. Between de Tolly and Kutuzov, the two main Russian Field Marshals, both pursued the infamous policy of trying to avoid any and all battles (de Tolly was removed for pursuing this policy and the Tsar actually put in Kutuzov just to shut the people who thought it was working up. Only for it to actually work) except when needed while doing the infamous Scorched Earth tactic. To give you an idea, Napoleon attacked the city of Smolensk expecting to relive his men with supplies taken there. Knowing that to Russia, the city was a very important cultural city full of monuments they probably wouldn't want it to be destroyed. Only for the garrison to continue fighting until the entire city was on fire and Napoleon couldn't even garrison the city it was so well destroyed.

But that is not to say that was the only thing they did. Most infamously, under Bagration, the Russians also started using Partisans, or citizens militia, who would attack French supply lines and even occasionally skirmished with them (kinda like the Soviet policy of deep battle doctrine). Bagration went on to create the first manual on how to conduct guerrilla warfare.

1.Napoleons army had to rely on foraging. This was made almost impossible because the Russians destroyed most of the crops and took the live stock.

2.The summer heat and the long periods of marching was one of the leading causes for most of the loses during the early days of the invasion.

3.Napoleons plan at borodino was not brilliant. It was basically a frontal assault. This made it easy for the Russians to escape. Napoleon also did not know the exact strength of the Russians so he did not bother to chase them.

4.Regarding the the old guard Napoleon did not know the enemy strength so he did not want to risk his guard going into a trap. It's hard to say if it would of broken the Russians or not .

hi! not discouraging further responses, but you may be interested in these similar posts:

general:

• How prepared was Napoleon when he invaded Russia?

• In what ways were the weaknesses of Napoleon's Grand Armee, and the way in which it conducted itself, exposed during the Russian campaign of 1812?

• thread in Wednesday AMA: Russia and the Soviet Union.

• thread in AMA on the Napoleonic Wars

• Napoleon invaded Russia with 685,000 men, but by the Battle at Borodino he was only able to commit around 150,000. Was this expected by Napoleon?

questions about winter/weather:

• Was it really the Russian Winter that stopped Napoleon and Hitler's invasions?

• Is the idea of "Russian winter" over-hyped?

• Was it the Russian Winter or Spring that were Hitler's & Napoleon's biggest enemy during invasion of Russia?

• Did Napoleon and the Nazis face winters of historic harshness in 1812-13 and 1941-42?

• Russian winter.

scorched earth tactics:

• A few questions about scorched earth during Napoleon's invasion of Russia