Need opinion and advices in BF noob

First I'm 1250 probably 11. Now I saw in a lot of games people wall near my base, specially in NR games. I gave the rule, no attack unless something like that happens, and don't touch enemy base until the time marc. But I've seen people walling in NR games near my base, " getting " extra resourses, is it useful or useless, I mean in terms of iddle time,l. Ok I won't drush him but my FC WILL go faster than his, and my siege will open his wall eventually. So, what's the best strategy in BF?