Go to game settings and set "Enable Developer Console" to "Yes"

To change the bind to open console (its default is the " ` " key, to the left of the num bar, and above tab), go to Options->Keyboard and Mouse-> Scroll all the way to the botom, and the last one should be Toggle Console

Commands for preperation.
Example: Command-Explanation

• sv_cheats 1-Required for most of the follow commands (warning, allows players in server to use god mode, noclip, ect.)
  
• mp_roundtime X-Sets round time in most gamemodes (besides comp) to X minutes (max of 60)
  
• mp_roundtime_defuse X-Sets comp gamemode's round time on bomb site maps to X minutes(max of 60)
  
• mp_roundtime_hostage X-Sets comp gamemode's round time on hostage maps to 60 minutes(max of 60)
  
• mp_buy_anywhere 1-Allows you to buy anywhere (I think it also extends buy time)
  
• mp_buytime 9999-Allows you to buy within the buyzone for 9999 seconds.
  
• mp_limitteams 0-Unlimited players on teams.
  
• mp_autoteambalance 0-Allows you to have more players on one team than the other.
  
• mp_freezetime 0-Removes the delay at the start of the round.
  
• mp_round_restart_delay X-Changes the delay at the end of the round to X
  
• mp_ignore_round_win_conditions 1-Makes the round last forever.
  
• mp_respawn_immunitytime X-Changes the time that players are invinsible on respawn to X
  
• mp_respawn_on_death_ct 1-Causes Counter Terrorists to respawn when they die.
  
• mp_respawn_on_death_t 1-Causes Terrorists to respawn when they die.
  
• mp_respawnwavetime_ct X-Changes time between respawn waves for CTs to X
  
• mp_respawnwavetime_t X-Changes time between respawn waves for Ts to X
  
• mp_use_respawn_waves 1-Use respawn waves.
  
• mp_warmup_start-Starts warmup :P
  
• mp_warmup_end-Ends Warmup :P
  
• mp_warmuptime X-Sets the length of warmup to X seconds.(doesnt have a minimum, so can be used for infinitely long warmups with 999999 or somthing)
  
• sv_infinite_ammo 1-Allows infinite ammo without reloading
  
• sv_infinite_ammo 2-Allows infinite ammo with reloading
  
• sv_showimpacts 1-Shows shot imapcts on walls.
  
• sv_showimpacts_time 5-How long those impacts stay visible.
  
• sv_grenade_trajectory 1-Shows trajectory of grenades.
  
• sv_grenade_trajectory_time 20-How long those trajectories stay visible.
  
• mp_free_armour 1-Spawn in with armor (0 to disable)
  
• mp_maxmoney X-Makes X the max money (default 16000 for comp)
  
• mp_startmoney 999999-Makes you have X money at start of game.
  
• command-Explanation
  
• command-Explanation
  
• command-Explanation
  
• command-Explanation
  
• command-Explanation

• bot_kick-Kicks all bots in the lobby
  
• bot_stop 1 -Freezes all bots (makes them stand still).
  
• bot_knives_only 1-Makes bots go knives only.
  
• bot_add_t-Adds a bot to the Terrorist Team
  
• bot_add_ct -Adds a bot to the Counter Terrorist Team
  
• bot_allow_rogue 1-Allows bots to go alone, rather than stick together.
  
• bot_kill-Kills bots.
  
• bot_difficulty [0-3]Bot AI difficulty. 0 = easy, 1 = normal, 2 = hard, 3 = harder[/b]-[/list]
  
• command-Explanation

• give weapon_[Weapons Name]-Spawns in [Weapons Name] At your location.
  
  Weapons List:
  • ak47
    
  • aug
    
  • awp
    
  • bizon
    
  • deagle
    
  • decoy
    
  • elite
    
  • famas
    
  • fiveseven
    
  • flashbang
    
  • g3sg1
    
  • galilar
    
  • glock
    
  • hegrenade
    
  • hkp2000
    
  • m249
    
  • m4a1
    
  • m4a1_silencer
    
  • mac10
    
  • mag7
    
  • molotov
    
  • mp5navy
    
  • mp7
    
  • mp9
    
  • negev
    
  • nova
    
  • nova
    
  • p250
    
  • p90
    
  • sawedoff
    
  • scar20
    
  • sg552
    
  • smokegrenade
    
  • ssg08
    
  • tec9
    
  • ump45
    
  • usp_silencer
    
  • xm1014

[WIP]

Copy and paste the entire list into console

mp_autoteambalance 0 ;mp_limitteams 0 - Allows players to join any team (incase you are having issues)

Bunnyhopping copy and paste!
Makes bunnyhopping much possible, also enables auto bunnyhopping if you hold space

sv_cheats 1;
sv_enablebunnyhopping 1;
sv_autobunnyhopping 1;
sv_staminamax 0;
sv_staminajumpcost 0;
sv_staminalandcost 0;
sv_staminarecoveryrate 0;
sv_airaccelerate 2000;
sv_accelerate_use_weapon_speed 0;
sv_maxvelocity 3500;

Surfing copy and paste!
Makes surfing about as easy as most servers

sv_cheats 1;
sv_accelerate 10;
sv_airaccelerate 800;
mp_spawnprotectiontime 0;
mp_ignore_round_win_conditions 1;
bot_kick;
god;

Perfect Accuracy
Removes recoil and bullet spread.

sv_cheats "1";
weapon_accuracy_nospread "1";
weapon_debug_spread_gap "1";
weapon_recoil_cooldown "0";
weapon_recoil_decay1_exp "99999";
weapon_recoil_decay2_exp "99999";
weapon_recoil_decay2_lin "99999";
weapon_recoil_scale "0";
weapon_recoil_suppression_shots "500";

Copy and paste the entire list into console

Bhopping commands along with perfect accuracy, with low gravity on a map with no skybox.
Reccomended Maps (without skybox)

sv_cheats 1;
sv_gravity 115;
sv_enablebunnyhopping 1;
sv_autobunnyhopping 1;
sv_staminamax 0;
sv_staminajumpcost 0;
sv_staminalandcost 0;
sv_staminarecoveryrate 0;
sv_airaccelerate 2000;
sv_accelerate_use_weapon_speed 0;
sv_maxvelocity 3500;
weapon_accuracy_nospread "1";
weapon_debug_spread_gap "1";
weapon_recoil_cooldown "0";
weapon_recoil_decay1_exp "99999";
weapon_recoil_decay2_exp "99999";
weapon_recoil_decay2_lin "99999";
weapon_recoil_scale "0";
weapon_recoil_suppression_shots "500";

Just auto bunnyhopping along with increased speed while Bhopping with norecoil/perfect accuracy commands

sv_cheats 1;
sv_enablebunnyhopping 1;
sv_autobunnyhopping 1;
sv_staminamax 0;
sv_staminajumpcost 0;
sv_staminalandcost 0;
sv_staminarecoveryrate 0;
sv_airaccelerate 2000;
sv_accelerate_use_weapon_speed 0;
sv_maxvelocity 3500;
weapon_accuracy_nospread "1";
weapon_debug_spread_gap "1";
weapon_recoil_cooldown "0";
weapon_recoil_decay1_exp "99999";
weapon_recoil_decay2_exp "99999";
weapon_recoil_decay2_lin "99999";
weapon_recoil_scale "0";
weapon_recoil_suppression_shots "500";