On board glow set up ... anything handy I can share.

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This setup is switched off when the throttle is fully closed; it switches on between fully closed and idle; and off again at about one-fourth throttle. You don't need glow in the range from one-fourth to full power.

This is the material you need:

The battery costs you some, the rest is peanuts. Battery from the hobby shop, the other stuff you can buy at an electronics shop.

Here's my throttle servo. A piece of ply is used to epoxy the microswitch just below the servo wheel. I used a large diameter servo wheel without holes in it; one side of this wheel is shaped into the switch activator. The activator's bottom edges are strongly bevelled and rounded, so it slides over the switch easily.

On board glow set up, micro-switch applied to servo

This servo-microswitch combi is the first to build. The center of the microswitch's switch must be positioned at the center of the servowheel (see image).
When the epoxy is cured, put the wheel on the servo, plug the servo into the receiver, get your transmitter and mark at the bottom of the wheel the positions of fully closed and half throttle. Shape the activator and bevel the bottom edges. Do this oversized; it is hard to tell where the switch will activate at the bevelled edges. This you will have to find out carefully: put the wheel back on, get your transmitter, test it, take the wheel of, sand a bit more and repeat... repeat... repeat... When you come close, you will have to fasten the wheel with its screw every time you test it, because this will make a difference.

On board glow set up, the servo wheel shaped into actuator of the switch

In the end, the switch should click between idle and fully closed; and at about one-fourth throttle. The first has to be accurate! It is very important the glow is off when you cut down your engine!

Next, measure deflections/movements and calculate the exact position of the ball-link.

Off course it is not possible to adjust your servo by programming your transmitter, after you finished the servo-microswitch combi. Any adjustments must be made to the pushrod.

To attach the wire to the glow plug you can obtain several clips from the hobby shops, but it's just as fine and much cheaper to use the metal part of a double entry electrical wire connector.

On board glow set up, wire connector

First take a piece of shrinking isolation tube, stretch one side so it will fit over the wire connector and bolt. Put it over the electric wire coming from the microswitch and clamp the wire into the connector. Move the shrinking tube half over the connector and shrink it. The shrinking tube prevents the wire from vibration and breakage (for a very long time at least). Before clamping the connector to the glow plug, I put a thin nylon washer to the plug, to make sure it doesn't make a short circuit.

On board glow set up, wire connector attached to glow plug

Solder a copper tube terminal to the other wire coming from the battery and attach it with one of the engine's mounting bolts. I soldered an extra pair of wires to plus and minus of the battery, to have an independent charging socket.

One more important note: your glow battery must be located as far as possible, preferably 10 inches, from your receiver+battery. Close up they will interfere. Also keep the throttle servo and wiring apart from the rest of your system as much as possible.
I have my glow battery just behind the firewall; throttle servo in the cabin at the left; receiver + battery at the right; elevator and rudder servo behind ... no problem!

Make sure you develop a new starting routine. Remember: your throttle stick is your glow switch as well. Say out loud: "glow on" ... "glow off". You don't want to be surprised by your on board glow when turning your prop for whatever reason.

I do it this way: After landing I kill my engine with the engine-kill-switch on my transmitter (throttle fully closed / glow off). I keep my thumb on the kill-switch and say out loud "glow off" while switching the receiver off. Everything is off and I know my on board glow is off.
For a next flight, I refuel my tank and prime my engine. Put my throttle stick to throttle open (glow off), switch on transmitter and receiver. I know glow is off. I say it out loud. I check my engine for a possible fuel-lock like I explained earlier. I put my stick to idle, say out loud "glow on" and start my engine.
If the engine has trouble starting... stick to full throttle, out loud "glow off"; check the engine; stick to idle, out loud "glow on"; try again; etcetera.

As a rule: when not flying, my throttle is always closed, glow off.

A more simple setup will off course be: no microswitch attached to your throttle servo, a simple switch instead to be activated from the outside. Nothing wrong with that, except for the battery being dead weight during flight and no 'flame-out prevention'.
Some people keep the switch on while flying for continues glowing. I think this is bad practice. I think the engine won't tell you how it's running, won't tell you whether the needle-valve adjustment is right.