Definitely good advice, but I have found in poker there is no Never Do This Or Never Do That, because almost any style can win.
For me, I don't recommend it, but I limp like crazy all over the place with suited connectors, AA, KK, QQ, any pair, etc. Yeah, I have to limp fold sometimes, I have to limp call fold sometimes. But you can mix it up with tight play and make the people who start raising behind you pay. I guarantee you, once they see you limp UTG with AA, they are careful messing with you when you limp some more, especially if you are a tight player. And when you find MANY of those players that can not fold AA or KK on the flop to a big raise, and you hit your 2 pair or set on the flop, the double-up that follows more than makes up for the folded chip wasting hands.

I think the key here is to be able to play well post-flop.
I probably tend to raise a little more often once I get to 200NL and above, but everything is dependent on the table I am playing on. More aggressive, more limping; more tight, more raising.
I do love that advice on 2x raising and 2x 3-betting, it just sets you up for mostly really small wins and really big losses (sometimes you will get a big win), plus many people will put you on AA or KK and trap you and force you to call a huge bet, and many call it. Of course, like anything, 2xing may make sense in some cases (with a suited connector). Make them think you have big when you have small.... (good advice on women and poker) :marchmell