maybe the music is not intended for a click
I nearly always record with a click, and the most helpful way for me is to set up a looped drum pattern which later can be discarded.
However, there are two situations that make working with a click difficult.
1 The first is where the track itself needs to change tempo because of the nature of the music. A conductor has the role of interpreting a piece of music and conveying changes to the orchestra by means of his baton, but a click track doesn't understand this. I have worked around this by using a temp editor to speed up and slow down, and so now the click track follows this. But I have to be pretty confident about the structure of the song to be able to do this.
2 The second is where a performer works to an internal rhythm. Most people I have worked with can adjust to (if they are not already familiar with) a click track. However, there are a few for whom the click track is 'invisible'. They start off okay, but quickly drift all round it. In part, this is because they internalise the rhythm, so that they play along to something they hear in their head, and somehow their ears become disconnected from the rhythm that's been set up. I guess that it's these people who need to practice to a click track, but sometimes I'm convinced that they are just not going to do it.
There are a number of ways to deal with this.
1 Forget the click. Allow them to play to an internal rhythm. This makes editing dificult, and likewise, others who have to perform later may have difficulty. I prefer a click, but I can accompany a free form track.
2 Forget the click, but remap the tempo afterwards (i.e. build the click around what has been performed). I've done this as well. With some applications it is easier than others. Some will provide a tap-tempo facility so that you can tap out the rhyhm along with the track to set the tempo. Other applications you have to do this manually by examing the waves and adjust the tempo almost bar by bar to line up with the performed rhythm. I've done this too. It's slow and tedious.
3 Pre-prepare a structure. This is a bit like setting up a drum loop, but you also add other instruments. I've worked out how the track goes, recorded a drum loop, a bass track and a guitar, then got the performer to play along to this. Again, this is a lot of work.
Clearly, it's best if the performer can track well to a click. And it it's you doing the performing, you don't often have others to straighten you out . . . so you have to do it yourself. In this case, the only answer is to find something that works best for you ( a metronome, a drum loop or whatever) and just plug away at that practice.