Agreeing terms for the sale of the land between the landowner and developer is my primary involvement, although I am quite involved with the planning process as well.
As mentioned above, I believe choosing the right planning consultant to write a well put together supporting statement is key. Another helpful tip would be to address any issue the LPA may have before submitting the planning application, if there are trees in the vicinity of where a build is going to take place, have a tree survey done to identify how valuable they may be. It is usually a good idea to remove trees (and have the stumps ground down) that could risk having a TPO put on them before submitting.
If you are having trouble achieving the desired approval/have had a refusal, a creative solution is to search for different applications within the locality that are similar to your own but have been approved (whether at delegated powers stage or at appeal. Use them to argue your case and some planning officers will back down.
Neighbours can also be a challenge, many don't like change even if a new development will improve the street scene and area. Tread with caution depending on what you are planning, trying to get them on side too early can backfire. For example if they are against what's being proposed and you do have mature trees on site, they may call in the council and have TPO's slapped on before you get a chance to do anything and your plans are scuppered once that happens.