I recently had a job involving a lot of punch in recording vocal dubs. When I do it the basic way - that is pressing Play, then Rec on punch in spot - the key is to start plenty in advance, since I don't want to miss the breath leading to the beginning note.
What I found myself missing was the ability to let the recording musician hear the few first notes of the previous recording - while at the same time recording the new overdub (plenty in advance).
And I really don't want to create a new track pr dub...
1 Set a short cut for "Time Selection: Set start point"
2 Right click rec button, choose "Recording mode: time selection auto punch"
3 Set the time selection very late
4 Begin recording.
5 Punch in with "Time Selection: Set start point"
6 Pull left side of the item to reveal all the recorded content and make a pretty transition.
The cool thing is you can just leave the time selection if doing more takes.
Also, punch out with "Time Selection: Set end point".
Screenshot recording:
https://stash.reaper.fm/21793/punch%20in%20trick.gif