First Tweak:

1) Go to CStrike folder  and create a file name minlag.cfg

2)paste the following codes to that file

alias "dslow" "rate 2500;cl_updaterate 10;cl_cmdrate 10;ex_interp 0.100; echo d slow speed"

 alias "vslow" "rate 3500;cl_updaterate 13;cl_cmdrate 13;ex_interp 0.077; echo very slow speed"

alias "slow" "rate 5000;cl_updaterate 15;cl_cmdrate 15;ex_interp 0.068; echo slow speed"

alias "norm" "rate 7500;cl_updaterate 20;cl_cmdrate 30;ex_interp 0.050; echo normal speed"

alias "fast" "rate 9999;cl_updaterate 30;cl_cmdrate 40;ex_interp 0.034; echo fast speed"

alias "vfast" "rate 20000;cl_updaterate 60;cl_cmdrate 60;ex_interp 0.017; echo wtf speed :P"

alias "lfast" "rate 20000;cl_updaterate 100;cl_cmdrate 100;ex_interp 0.010; echo LAN speed"

alias "rates" "rate;cl_updaterate;cl_cmdrate;ex_interp"

3)Once done with the above steps -- run your cs and in console write the command "exec minlag.cfg"

4)After you`ve executed the .cfg file you can use the folowing commands:

- dslow if your lag is bigger than 500

- vslow if your lag is bigger than 400.

- slow if your lag is bigger than 300.

- norm if your lag is between 150 - 300.

- fast if your lag is between 100 - 200.

- vfast if your lag is between 50 - 100.

- lvast if you are on a LAN server or 'localhost server'

But remember wrong choice may increase the lag    . And its just a tweak .If  the problem is with your connection then nothing can minimize the lag.

Second Tweak:

While in game type in the console "cl_minmodels 1" . It will load only two models in the game . One for CT and another for T . Reducing the no. of models results in low consumption of bandwidth which reduces lag .