This depends on the meeting etiquette. Here are some suggestions:
If everything goes through the chair, you need to indicate to the chair you have a point to make (e.g. raise your hand).
If the chair wants to move on from the topic or close the meeting before you've had a chance to make your point, you should say something like "Sorry, but I don't think we've fully considered [your point]".
If others are talking at length, you should wait until there is a suitable pause (even those really proficient at filibustering have to draw breath some time).
If you and another person try to raise a point at the same time and you say "No, you go first" - the other will usually reciprocate and make space for your remarks after they've spoken.