NB: ArkhamDB now incorporates errata from the Arkham Horror FAQ in its card text, so the ArkhamDB text and the card image above differ, as the ArkhamDB text has been edited to contain this erratum (updated August 2022): Erratum: This card's $reaction ability should read: "... attach them facedown to Stick to the Plan." - FAQ, v.2.0, August 2022
"As If": This was added to the FAQ (v.1.7, March 2020) and then amended (v.1.8, October 2020). You can read the October ruling on the ArkhamDB rules page here. (I'm adding a hyperlink rather than retyping the rules in case in future the ruling is changed or amended - at that point, the rules page will be updated and all ArkhamDB FAQ entries will link to the correct ruling.)
Before you draw your opening hand: Search your deck for up to 3 different Tactic and/or Supply events, and attach them facedown to Stick to the Plan. Shuffle your deck.
Cards attached to Stick to the Plan may be played as if they were in your hand. As an additional cost to play an attached card, exhaust Stick to the Plan.
Here's a handy link to a search of all the plans that can be stuck with: arkhamdb.com
Enjoy your plans. Plans are good. Plans are nice. I like plans. Am I over 200 characters yet?
One extra cool thing about Stick to the Plan that nobody else seems to be mentioning here:
For Roland Banks, Zoey Samaras and Carolyn Fern - you can include one copy of Astounding Revelation in your deck. This will trigger when you do your initial search with Stick to the Plan, causing you to consistently start every scenario with 2 extra resources (and your deck is thinned by one extra card!). This is equivalent to having Another Day, Another Dollar, for free!
Like most Permanents, Stick to the Plan is really good. It basically says you start the game with three extra good cards in your hand. What's more, you can choose cards to let you consistently execute specific strategies. Here are some possibilities for our three Guardians (not all of these cards are legal for all of them):
Emergency Cache, Ever Vigilant: These cards are very powerful on turn 1 as they let you set up far faster. Now you can start with one (or both) every game. Ever Vigilant, in particular, is a gamechanger for asset-heavy Guardian decks. Guardians have (except for Zoey) hitherto struggled to pay for all their powerful, expensive assets; with Stick to the Plan I think those struggles are mostly a thing of the past.
Extra Ammunition: Starting with this is a huge boon to any investigator who's running a Lightning Gun or Shotgun deck, since it basically doubles the power of those (already very powerful) cards. Goes well with the two options above, since Prepared for the Worst will help you find your gun and an economy card will help you afford it. Then you can load it up. Zoey could even take Contraband for even more ammo, theoretically. You can fetch the upcoming "Eat lead!" to complement your Extra Ammunition, too, if you want.
Shortcut: The upgraded Shortcut just dominates certain maps, especially those with a central nexus location you have to travel through repeatedly. With this Roland can always get the upgraded Shortcut down on turn 1.
Elusive, Dynamite Blast: These are really powerful but slightly situational events, and they're pretty nice things to have in your back pocket. If you have foreknowledge of the scenario, you might know in advance if one of them is going to be needed.
6 XP is a lot, but I think this card offers so much power and consistency to a deck that most Guardians will want to pick it up sooner rather than later.
One of the absolute best things Tommy can stick to the plan at the moment is a flare.
If you manage to flare an agency backup into play early, you are set for quite some time.
But with enough targets in your deck, you aren't going to be disappointed to flare into play a beatcop or brother xavier.
Re: Lola and this card, confirmed from Fantasy Flight rules enquiries: "...though Lola technically has access to Stick to the Plan, at the time its ability would be triggered, she has not yet chosen a starting role and therefore cannot trigger the ability on Stick to the Plan (rendering it rather useless for her). Matthew Newman."
6 XP feels substantial, but if you stick 3 high XP event cards on it, now it is like you no longer need to buy 2x copies of them. The more expensive, the more XP savings.
Even if they aren't quite adding up to 6 XP, still 2x copies won't offer perfect consistency. (but offering a chance to potentially use the events 2 times, as opposed to buying 1x to stick.) Even, even so, 1x copy to stick has an advantage that you have more deck space to do something else, and these 3 event cards are thinned out immediately, then improve consistency of the other 2x copies / your signature card a little bit.
(Underworld Support thins out 5 cards on highlander penalty and you can feel the impact of finding signature/exceptionals/1x purchases faster, this card which thins out 3 could also be think of as a lite version.)
If Mandy Thompson is teamed up with a Guardian investigator, would that investigator get to draw 4 cards to put under Stick to the Plan? Edit: I have found out. At the time when you draw your opening hands, you haven’t yet read or set up the scenario so aren’t yet at a location. I think.