These days, more and more people are playing 2/1 GF. My hope is that it won't be long before only dinosaurs are playing the "old way" -- where a 2/1 response can be only 10 points as opposed to an opening bid.
Now that most of the world is on board, can we unify them?
If you sit down with a new partner and ask: "2/1 GF?" and they say "Yes" -- that is a good start, but not complete. Analogy: You can't just ask: "RKC?" and hear "Yes." You have to agree on such things as 1430 (Yes/no), Queen ask (Yes/no and how), How do you ask for kings (specific/#/other)? etc.
There are some areas within 2/1 GF that are played differently depending on who you learn from. There is no right or wrong, but I have my opinions, and I suggest the checklist below (with my way indicated).
Warning: This is for experienced players with good memories, willing to put in the work. This can't be casually digested. The list below was modified by me in 2018. At the end, is also a summary of a poll I conducted on Bridgewinners.com
AREAS OF 2/1 GF NOT UNIFIED
1 1NT forcing or semi-forcing: I suggest Semi-forcing. There are pros and cons. Click here to read more.
2 Opener's Reverse: I suggest it can be done with a dead minimum. Example: 1
-2
-2
can be bid with:
AQ76 KQJ65 2 
J32.
3 Opener's 3-of-a-new suit (closely related to #2): I suggest this can be done with a dead minimum. Example:
1-2-3 can be bid with:
A8652 65 42 AKJ2.
(The general theme which is building is that I like opener to show his shape--without regard for strength. My emphasis is on first finding the right game/strain--and exploring for slam later).
4 Opener’s jump rebid: I recommend that it promises a solid or semi-solid 6+ card suit (at least AKQJxx or KQJ10xx) -- but does not guarantee extras. Example 1-2-3 can be bid with:
K2 AKQJ105 32 862.
Opener should not jump because he has extra values! Don't preempt your own exploration. Go slowly. Jump only with a solid suit, fast arrival weakness (see #5) or a splinter bid (see #6).
5 Fast arrival: Jump to 4, 4, 5 or 5 (in a previously bid suit) by either player is always the weakest action. Go slower with extras. But, jumps to 3NT show extras—(mild slam interest). {There is a long complex reason as to why a jump to 3NT should show extras, while a jump to a suit-game should deny extras--please take my word for it.}
6 Splinters: Opener's Jump Shift is a Splinter and does not promise extras. Example: 1-2-3 with
AQ765 A43 2 Q876.
7 Rebid of 2 of opener's major: Tends to promise 6+ cards. Rebid a 5-card suit only if really stuck (see #8).
8 Rebid by opener of 2NT: Shows 5-3-3-2 and doesn’t guarantee everything stopped–but don't have two low cards in an unbid suit. So, rebid 2NT after 1-2 with:
J52 KJ765 52 AK2
but not with:
Q52 KJ765 AK2 65 (raise to 3) and not with:
AQ2 KQJ98 852 32 (rebid 2 as least of evils -- a rare time I would rebid a 5-card major--the suit would have to be very good).
9 4th suit by responder is not natural. Just a "punt" or saying "I don't know what to do next." Usually, it will be a hand without a stopper in the 4th suit. Example: 1-2-2-2 is something like:
42 762 A43 AKJ32.
10 After 1-2 : Opener rebids 2 with 5+ diamonds (says nothing else about his hand). Without 5, he bids naturally (including showing a 4-card major up the line without promising extra values). Opener's rebid of 2 or 2 simply shows 4-card majors up the line (and denies 5 diamonds). Extras not promised (see #2).
11 Is 2/1 completely (100%) GF?
Yes.
On all 11 items above, there are other ways to play. I don't wish to debate what is best, but rather to suggest you choose one way or the other. There will be "wins" and "losses" for each particular style adapted. My way is based mostly on the theory of: "Find our trump fit as quickly as possible." Worry later about slam. I think each item listed is the easiest/simplest way to play -- and quite possibly all 11 are also the best way to play. Advanced players can/should learn "Serious 3NT" (or Non-Serious) to help with the game versus slam decision.
Note: This list requires work. There is no way around putting in study, memorization, partnership work and a few headaches. Sorry.
Now, when you ask a new partner 2/1 GF? Have them answer "YES" -- but also go through the checklist. Or, if you are both on my "page" you can just agree "LC way" and not have to go through each item.
BMS 2/1 Webinars by Michael Berkowitz
Results of 2018 Bridgewinners poll