One thing that does not seem mentioned above... whichever you join, and whatever you say on the radio, in general you need to arrange your join to "fit in" with the current circuit, and departing traffic i.e. these have right of way over you. Keep clear of the circuit until you can see all traffic, and arrange your join accordingly. If it is too busy, then just keep clear.
If it is "controlled" things might alter somewhat... but everybody needs to be sure who is "controlling" and responsible for collision avoidance.
I find the OHJ a "pain", but there is little to better it for a good look at the circuit, and ability to adjust to fit in...
NoD