Opening Bid: One No Trump --- 15-16 HCP
Players who use a forcing club system frequently use a different point-count range for the opening bid of 1NT, with a range of 14-16 being the most popular, but 13-15 is also often used. Most players are comfortable with the 15-17 range and prefer to continue with that agreement. We use 15-16 points and agree that most often we do not have a 4-card major, but never say never.
Why only a 2-point range? Because it eliminates the need for responder to make an invitational bid. Responder can almost always decide whether to pass or bid game when she knows her partner's point-count that closely.
2-Level and 3-Level Responses
There's a really big advantage to using only a 2-point range in other ways, as well. The main one is being able to respond in any of the four suits at the 2-level with the agreement that it is not forcing! The opener should pass any 2-level bid by her partner.
And finally, just in case there is a hand where responder is not sure, she can bid 2NT as a forcing bid. This is a way of discovering a 4-card major in the opener's hand. (A major should be rare, though. Consider opening 1 with with a 4-card major to give partner the chance to show it at a low level.) We treat the 2NT response like a Stayman call, except the opener rebids her best minor to deny a major.
Double by an Opponent
Something simple - Redouble with 10+ points.