Yea im a firm opponent of mixing things up. The ideal way to disguise your hands is to play everything exactly the same. If you mix it up ppl have more of an idea what you are holding but if you are just as likely to raise 89s/JT etc in position as AK, then ppl have a very hard time trying to figure out whether or not the flop hit you.
HU is a perfect example. If you raise everytime, cbet basically everytime then ppl have no clue whether you have air or hit 2 pair.
Anyways as for original post...raise your standard amount unless you are at a very aggressive table where you know somebody is going to raise you further down, in which case you can limp/raise. But the worst thing that could ever happen is that you have AA OOP in a multiway limped pot.