Borders Boost Delay trick
If you didn't know, you can actually swap what you're researching. If you click on it you'll have the same cards and you can change what you're researching while keeping spent flasks on the one you had. So you can pre-research other techs before you research the one-time Gold bonus card you want, but not now. This is mostly only useful for Borders Boost. Maybe Happiness Boost, but that's usually much later in the game, or Civics Boost if you're at cap and about to spend. Or Orders Boost if you are starting a war in a couple of turns.
Does the tech deck offer you Border Boost but you still have some other cities coming online soon and the other techs aren't urgent?
Prebuild Border Boost until it is one turn left, then click to switch tech. Repeat for that one (so it's not discovered, discarding your gold card). Switch back to Border Boost once you get out that settler that was on its way. You delayed a couple turns, but didn't lose any research. Be careful of any events (or Steal Tech missions).
This is especially useful for Carthage, that's cursed with starting the game knowing Aristocracy, and thus has Border Boost in your starting deck when you only have the one city.