For this method you will not be boosting as this is a very not legit way of playing the game, and I would not recommend boosting to anyone that doesn't want their account to be deranked or even banned!

This method you could call cheating. It uses the map shipment in the game and you play it over and over. It may be very boring but after all, you are in this to level up fast and maybe not necessary use the game to it's funniest potential as this game is extremely fun to play! You also need to be ok at the game to level up, it is not a cheat and you still have to get kills to level up. Just a method to level by playing a very small map which is leading to more kills.

Step 1: You will need to gather a party of six. You can do this multiple ways. You could just invite all your friends to play it over and over. You could also make a post in the modern warfare remastered section and say "Shipment 24/7 | ADD Chocolate". All you need to do is find people and get a party of six then you can move on to the next step.

Step 2: Once you have all the people in the game, you will need to start a game of domination. You will back out with your party and keep doing this until you find shipment in the left side where you can vote for the map. Since you have a party of six, people that are just looking for a game will join you because it can't find a game with 6 available spots on one team so people join you. If you don't find people and you merge into another lobby, don't worry as this might happen very frequent in the night time and you just have to look for another lobby of shipment.

Step 3: This is probably the most easy step but I am not saying that the other ones were very fast either. You vote the map with people in the game and it will start the map. Have fun on trying to level up as much as you can!