I had the opportunity to read many overtures at the PC(USA) 223rdGeneral Assembly and to discuss several in committee. I noticed some things that I think will help future writers of overtures do a more effective job which will result in the overture being approved perhaps with little to no modification.
First, keep your initial audience in mind. Committee members are fellow Presbyterians. This means they are independent thinkers, educated, and want to produce a good product. If your overture is not well-written, it will not be considered at length.
If the research supplied is of poor quality and quantity then it will likely not even be taken seriously. On my committee, we had several Ph.Ds. and all of them have done research. We know primary sources and Wikipedia is not it. We also give little attention to opinion articles regardless of where they are written. If you are trying to lend support to your overture, make sure the research is sound, from primary sources, and supports your case. I recall one in which a statement was used to support the overture but it came from a source, out of context, that actually refuted the overture.
You should also use the latest, correct terminology. Our language is fluid and the term in vogue today, may not be tomorrow. Making sure it is correct saves the committee or the entire GA having to amend it.
I also believe overtures should be short and speak to the point. If there are several important points to be made, I think offering several overtures is preferable to offering one very long overture. The longer the overture is, the more difficult it can be to understand. If it is too long, it also may never be read completely. So, make it short and strong addressing only one or two points.
You also need to fully define your terms and vocabulary. This was a major issue with the fossil fuel divestment overtures at this GA. It was not entirely clear what was trying to be divested. Was it the production of fossil fuels from the ground or was it the refinement or burning of those fuels? My sense is that the authors were actually more concerned about the effects of greenhouse gases that result from burning those fuels. However, the authors failed to account for the many products made from oil, for example, such as plastics, asphalt, medications, etc. The lack of specificity resulted in the defeat of those overtures.
Finally, recognize and attempt to address counter-arguments in the discussion of the overture. If there are several ways to achieve the same objective, note why your method is superior and point out the shortcomings of the other methods.