It really depends on the type of aggressively/bluffy/station you're playing postflop.

If you see a weakness, attack it.  For example, you'd adjust different vs a guy that calls just the flop really loosely, compared to a guy that will call on every street loose.  For the loose flop player, you can fire two barrels to push him off his weak hand range, for the guy that calls down super light, you'll just be value betting mostly, and value betting thinner than usual (firing 2-3 barrels with weaker pairs more often, and for value).

Generally, players won't call 3 streets super light, so if you notice them calling wide preflop and not folding on the flop, give two barrels a try.  Yes, you lose sometimes, but you win more than enough to make it correct.  When you lose the pot, you gain reads and can adjust more precisely and give yourself a good chance to win the match.  If you win, you may not have as much information, but two things are certain 1) You won the pot, so you have a lead and 2) They folded, you were the aggressor and they are likely more frustrated than they were when starting this match.  

The donk bet is not always weak at all.

Two types of common donk bettors come to mind that you don't want to raise as "weak" too often:

1) The guy that donk bets with his strong hands.  This is laughably exploitable, but you have to recognize it.  Their range vs cbets is very weak then, so when they check call the flop, you're often firing 2 or even 3 barrels, knowing they likely would've donked their stronger hands.  You can't do much except play your pot odds and implied odds vs these guys when they donk, call with odds that make sense and hands that can likely draw out on them, or call with stronger hands that have good showdown value.  Fold weaker garbage and don't bluff these leads, as they don't contain much fold equity.

2) The guy that donks with any piece.  This is actually fairly common too in the lower stakes.  Players will donk bet draws, weak pairs and sometimes stronger pairs.  Even if they check raise strong hands, when they check to you their range is still too weak, as their donk bets consist of a lot of the hands that hit flops.  If a player can only have a strong hand or a weak hand, you just cbet all day and probably check back most turns (since a call would mean they are strong, unless they CR their strength on the flop, in which case a call is likely a very very narrow range like a certain type of draw or pair, that you in turn play accordingly and likely fire the turn a lot at).

Vs these donk bets, you can take various lines with different hands.  You'll flat call more of your medium pairs probably, and value raise better pairs like top pairs and 2nd pairs because their range includes draws and all non top pair type hands.  You can fold your really poor draws unless they do something like min bet donk.  If you notice them folding to the "call flop, bet when they check turn" line, which happens more than you think and is really transparent and exploitable, then start to float weaker drawing type hands and fire them on the turn as a semi bluff with really good fold equity.

In the end, you really just want to think about exactly what villain is doing.  Players aren't similar enough to make a generalization such as "donk bets are weak," you'll spew too much against the two player types i just mentioned, and probably a few more that I did not.  It's great to classify players as tight, passive, aggressive, loose, and so on, but in reality a lot of these guys just show characteristics of each player type.  The surefire way to fully exploit somebody is to pay attention to exactly what they've done, and formulate a counter to that specific player.  Sometimes we as players take a too general approach to exploiting somebody.  We see they are loose and we make one adjustment, rather than paying attention to what spots they may deviate from loose play in, or what specific spots they are extremely loose in and how exactly they react on later streets with that loose range.  The more you pay attention to, the more information you have and the more likely you'll make a good and profitable decision against this player.

If you're playing a player that recklessly raises donk bets but doesn't always cbet... that could be a good play.

Usually check raising bottom 2 on a dry board is better though, especially against a player that is aware that you'll be check raising dry boards quite often.

Donk betting is very opponent dependent in my experience.  Apply the same thought process to this as you do to adjusting in other areas and you should start to see some good spots to donk out.