Top tips I have worked out....
1. Get your fire started with plenty of dry twigs and leaves, but you can add freshly cut material in reasonable quantities.
2. Use a tarpaulin under the section of hedge you are trimming, all the trimmings fall on it then you just drag it along to the next section and start again. Tarps slide along the ground with ease and twigs don't get caught in them. Then when there is enough clippings, bundle them up and take it away - Minimal raking, minimal mess

3. Burn as you go - I had thought you should always leave prunings to dry before burning but I now disagree. In Scotland we just don't get enough long spells of dry weather to allow prunings to dry outside at this time of year. So I have decided that you absolutely need to burn as you go. Otherwise we end up with mountains of half rotten prunings kicking about for over 2 years.