I am not getting .com/net/org for the keyword i am searching for. will it be a good idea to register other TLds mentioned above
.sc can be marketed as source like whois.sc, but remember use them only if your users are technically a bit advanced, otherwise you will lose lots of traffic to your .com counterpart
Unless you have very generic/valuable keyword, not worth the reg fee. Add a keyword to your search and the .com will get you more traffic. Even ccTLDs are a longshot. .de, .uk, .tv are the best of those but worth 10% of the same .com (in english for a Universal/US based audience)