Mayur, check out

http://web.ukonline.co.uk/sssrcsoaring/

An excellent resource on all things scale sailplane orientated. Although primarily devoted to scale sailplanes there is a great discussion group and lots of advice on towing/tow planes.

RoT (rule of thumb) big gliders, big tugs, long lines. Always put a release on both planes.

Have fun

Clive