Ok for demo boosting is my fav way. Theres two ways doing it.

"Stuff you will need"
Perks. Ninja. rest any other one
Guns. what ever you want there for contract if your killing and plant/defuse ect.
Tactical Insertion.

For just the plant and defuse way.
you need to time it perfect so when the bomb gets planted the other 2 players are already in the middle of defusing theres so this way it lasts along time. "this way is the team tactical way 4 players with 2 controllers "each".

For the killing and plant, defusing way.
you need to bring your self and your guest to the bomb the host as put you on. put down the tactical insertion on your guest and when your person is defusing or planting you kill him then hold x right away for fast pickup its harder but you end up getting kills and plants and defuses "Also This is for Team Tactical".

Extra info.
You will get 50k to 60k in 1 round of boosting this way i stop at 9500 score and end the game so i don't get reset. And for getting your players in the game tell them to join your session or send them a invite.
For me i like to just plant and defuse so there is no mix ups 8) Good luck and have fun if you have any other questions or need info Message me or post on this topic.

P.S This is my new TTG account forgot my other one and email for it add me back on here if you knew me on Ciggaro. + rep and thanks would be wonderful!