Note to Beginners Interested in 42 Tournament Competition
Forty-two (42), the four-player trick-taking domino game with bidding and trumps, was "invented" in Northeast Texas in the 1880s by some boys whose parents did not allow playing card games (associated with gambling). The boys patterned their domino game after the card game Whist, the same card game from which the card game Bridge was derived.
Bridge went on to become a world-class game because Bridge partnerships divulge their bidding and indicating conventions to their opponents to ensure a level playing field. The 42 community did not evolve in that direction, nor does there seem to be much interest in sharing private bidding and indicating tactics between competing 42 partnerships.
Forty-two (42) is less complicated than Bridge and much easier to learn. That is why it is so popular, mostly in Texas, Oklahoma, and New Mexico. Over the years, variations crept into the game. Thanks to the public internet in the 1990s, the National 42 Players Association (N42PA), founded in 2005, was facilitated in establishing straight 42 (no variations) as the standard in sanctioned tournaments.
Today, social 42 is still a fun game for family and friends to play, and it is played with diversified informal rules. However, when social players participate in sanctioned tournaments, the rules are for straight 42 as prescribed by the various tournament hosts. (Some indicating practices are not defined in the rules and, unlike Bridge, indicating methods do not have to be shared with opponents.)
This allows "creativity" in sanctioned tournament competition. Partnerships that are not familiar with unconventional indicating tactics are often disadvantaged against "street-wise" opponents. This is not a problem if winning is secondary to having fun. (Winnings have been as much as $2400 in one N42PA tournament that requires club membership and qualifying points to compete.)
Some players prefer definitized playing rules that are standardized and apply to all sanctioned tournaments. Some thoughts how to proceed are summarized here: Proposed Rules. As a beginner, you might not be ready for this conversation but, in time, as you gain playing experience (especially in tournaments), you will better understand its significance.
Some 42 players prefer the mystique of figuring out their opponents' subtle indications. As such, you, as a beginner, need to be vigilant. In the meantime, be advised that the only recognized 42 club that sanctions 42 tournaments is the N42PA, and its "official" rules apply only to tournaments that it hosts. (Other sanctioned tournaments have their own rules, some more definitive than others.)