The best way is to design it into paired units. Each unit of the pair has 1 landing runway and both share a single exit runway (since 100% utilization for take off is easy). Both are 3 tile long run ways and the entire thing (the paired section) is a strip. The length of each unit of the pair is up to you, you can have them 6 long for 12 landing bays if you want to park a lot of planes there. I generally recommend 3 long for 6 bays. A simple "landing only" unit could be as little as 1 length.
Sharing a common exit runway saves on maintenance since you can easily get twice the traffic leaving than landing due to how landing operates. The bays are all in a line to limit travel distance, 3 length for the parking line is a good trade off since you spend little distance on the ground and each bay is on the exit path (no back tracking). You need to place the one-way signs before building the far side bays because of a bug allowing a one-way intersection.
You normally cannot place signs on intersections but if you place the sign and promote it to an intersection it will have a one-way sign that functions as intended (one-way intersection, not allowing traffic back the way it came but allowing it to take any branch). Personally I would recommend this be made part of the standard placement of signs since it is so useful with airport placement, especially when designating land and take-off runways (important for airports).
Do not bother with more than one landing or take off runway per unit. Although it should be possible to specify which runways to use with waypoints this may only be in next release and even then has been reported to be kind of buggy. It is far easier and more efficient to have units with 1 entry and exit ramp using signs to control the flow, any other configuration needs extra ground ways which wastes money (especially pak64 where planes cost a fortune when on the ground).
Here is a text layout of a 12 bay functional unit, a unit intended for parking planes. Another is shown for a simple "land only" configuration.
W = Way for planes to move on ground.
R = Runway
B = Docking Bay
S = W with a one-way sign allowing traffic towards middle.
I strongly recommend that aircraft be forced to have a minimum run-way length in future. Such efficient units should not be possible for massive planes and overall airports are too easy to design and build currently.