Does mission order-of-completion matter?

I've started a new game of splinter cell blacklist, and so far only completed the first 2 campaign missions. (Intro + Save Andriy)

What I'm wondering is, should I be completing all option missions + all character conversations in between each campaign mission.

Aside from not earning the extra cash, will I miss out on anything in the storyline, that I can't get back to if I don't complete them as they're available. Or can I just wait til the end.

Solution 1:

You might have completed the game by now. But the optional missions are small side missions that interact indirectly with the main mission and story. They are not a must do, but a nice to do.

These missions are introduced via the conversations you can have with the crew unboard Echelon.

I whont get into details regarding the optional missions, those are for you to experience. But I would recommend doing so, as minor details are revealed.

The main story are in the main missions, so you will not miss out on anything.