The most common use of a 2♥/♠ opening is preemptive with a 6-card Major. We very often talk about the Wekk Two opening.

The description:

• 6-11 HCP, 2-3 Top Honors
• Most often semi-balanced hand 6322, 6331, but can be also 6421 with a 4-card minor
• 7-8 Theoretical Losers
• 1,5-2,5 Defensive Tricks
• Can be a wide range on the 3rd seat
• Shows 11-14 HCP, 7 TL on the 4th seat

The main purpose of this opening is to preempt opponents and be in the best contract for our side. The opening is very descriptive and the opener should not make any other action if partner is not asking for it. If you do bid a second time, you should have a goulash hand 65 with a minor. But, I do not advise you to bid like this and I also strongly discourage you to open 2♥/♠ with a 7-card suit.

First of all, analyze your hand and strength for a contract in partner's suit. Count the honors or covers and subtract them from partner's TL. That should give you quite a precise estimation of how high we want to go. Based on that, you can choose from the responses.

If you do not have a fit, you do not have any options to invite, unless you have 6-card in the other Major. That is one of the reasons why the opening should be very descriptive. If you have a GF hand, the most important information you can get is which shortness partner has, if any. 

We can use a jump to 4 in a minor to prepare for competitive bidding and give the opener a chance to make a decision if the opponents overbid. If the responder raises to 3M or 4M, the opener should always pass.

• 2NT = INV+ without 3+card fit, asking for SRT. We can stop only in 3 in a Major so do not use it with any 14-15 HCP hand, then see below
• 3♣ = GF+, 3+card fit, asking relay, then see below
• 3♦ = INV, 3+card fit, then open bid 3M with a minimum, 4M with a maximum
• 3♥/♠ raise = sign-off, 4-12 HCP, 2-3 tricks, 3-card fit
• 3NT = sign-off, can be with fit
• 4♣/♦ = fit jump, 5+card in the minor with 2 TH and 3+card fit
• 4♥/♠ raise = sign-off, 4-17 HCP, 2-5 tricks, 3+card fit

The opener shows a shortness unless he has a super minimum hand:

• 3 in new suit = 8-11 HCP, singleton in the suit, then new suit is natural and a slam try, 3M is to play
• 3♥/♠ = 6-8 HCP, minimum, can have shortness, but often without shortness, then new suit is natural and slam try
• 3NT = 9-11 HCP, no shortnees or singleton top honor, then see below

• 3♦ = maximum with a SRT, then 3♥/♠ ask for the shortness
• 3♥/♠ = 6-8 HCP, minimum, can have shortness, but often without shortness, then new suit is a control and slam try
• 3♥/♠ other Major = singleton and 6421 distribution, then 3NT ask for the 4-card
• 3NT = 9-11 HCP, no shortnees or singleton top honor, then see below
• 4♣/♦ = 9-11 HCP, 6421, doubleton in the other Major and we show the shortness