Opening at the 2-level

less than an opening hand, no more than 12TP, good 6-card suit, 2 honors in the suit. Suit quality is very important. A good rule of thumb is that you should have 2 of the top 4 honors. Intermediate cards are also important. AJ10975 is better than KQ5432. Having opened a weak 2, you should not bid again unless partner makes a forcing bid. Partner has enough information to know what to do.

This is the perfect hand to open 2s. You hope to make it difficult for your opponents to find their likely heart fit.

This is too good for a weak 2s. Open it 1s.

2NT shows 20-22 HCP and a balanced hand. It is a limit bid and therefore quite specific about its shape and its points.

This hand is ideal for a 2NT opening.

Having a 5-card minor does not make your hand unbalanced; the best opening is still 2NT.

0-3 = pass, 4+ = bid game

If partner opens 2NT, you only need 4 TP to bid to game. With a balanced hand, bid 3NT.

With a 6-card major, it will be safer to play in a suit contract. 2NT promises at least two hearts because it is balanced, so you know you have a fit. Bid 4h.