how to tie tomatos and cues to canes in pots.

It's not critical where you put your ties, just loosely loop soft twine or string round the cane and the plant and tie , every 8inches or so, i would guess.
(strips cut from ladies tights make nice soft material for tying up........not that I'm suggesting you wear them of course    )

just to give you another option....   3 is never enough. 

I use garden wire and wrap it gentle 4-5 times round both the cane and the stem, it gives enough support to hold the stem in place but as the stem expands it pushes the coils apart.