1. Alms requires that you have no treasures in play, this means buying Mint or gaining Mandarin can let you also Alms a card giving you a bonus $4 if you have a spare buy. For instance, a Margrave opening to trash Mint & Alms Remodel can go a long way very quickly.
2. It may be obvious, but Guide not only works with short hands from the Militia family (especially Gship) and Opost, it also works extremely well with trashing durations. Early game Guide/Amulet trashes a card which is the great "thin, but don't lose buying power" option ... without having to spend a $5. Late game, Transmogrify can go Duchy hunting (or Provinces with Peddlers, Plats, Princes, etc.) and then let you draw something better than green to kick off your turn.
3. There are a few options for tactical Quest openings. Save a card, then Quest the next turn. You can also Tfair up two curses, this is mostly useless but can be exceedingly strong in very rare cases where you can Tfair, Quest, and Alms something that likes to eat golds (e.g. Dev but also Smason).
4. Bonfire is nice for ridding your deck of problem cards. This is biggest with Possession (bonfire early Ambassadors or Masqs), but is also very useful for mandatory trashing if you have mandatory play going on (e.g. Tr engine, Golem, Herald).