re: Poker & $5 NLHE 6-max: Range to place Villain on / How to play river
I don't think "raise more preflop" is a universal rule, but it's probably a good idea.
Some things to consider:
1) NL5 is full of calling stations, so putting more money in the pot when you are sure you are ahead is never a bad idea.
2) If you always raise 3xBB for most of your hands and 4xBB for your premium hands, then it's pretty obvious what you are doing. The opps at your level may or may not notice. I play around that level and I'm constantly on the lookout for obvious AA and KK to setmine, but I'm not your ordinary NL5 player. Is there anyone at your table you fear giving this info away too?
3) If your table is rather tight and you are MP, it's not a bad idea to be aggressive pre-flop and just take it down there, rather than put yourself in an awkward spot OOP if the flop is ugly.
Raising more pre-flop is fine, especially at this level, but be thinking constantly about all the factors that go into a poker play, so you can be ready to move up soon.