Clogged toilet overflowed

: My toilet is clogged up – when I flushed it last night, the bowl filled nearly to the top before it stopped filling. This morning the water had drained enough that it was quite : low in the bowl. I used a plunger this evening which resulted in some black matter floating in the water, then I flushed it. Mistake! The water overflowed from the toilet bowl (fortunately not too much of a mess). Now I am uncertain what to do – I dont want another overflow! I read the thread on this forum about the people who had toilet problems because they flushed paper towels down their toilet – that is not the case here, nothing has been flushed that should not have been. I can try the plunger again, and possibly a bent hanger, but I am afraid that when I flush the toilet will overflow again. If it looks like it is going to overflow, will pulling up the float ball in the tank stop it? If so, will it just overflow anyway when I let the float ball down again? Should I try something other than a plunger or a wire coat hanger? Thank you for any advice you can give me on this problem.