Is it better to not do the whole Miranda vs jack fight till after the suicide mission
Technically it's doable. You need loyal Jack and keep not-loyal Miranda -Always- with you during assault on the Collector Base right to the very end of the mission.
Still I would advise against it to exclude any chance of Miranda dying (if Jack is not loyal she will die - pretty much guaranteed). Loyal Miranda cannot die.
Last time I play with a unloyal Miranda she and someone's else ended up dying and she apart of the crew that went back
Just built your paragon or renegade up. It's really easy to avoid issues like that just by working those systems. Also, get the skill upgrade that boosts paragon/renegade.
Side mission can give that to you right I've looked is up and every site I asked said no they don't help
My way of dealing with this is to leave Miranda or Jack loyalty mission as late as possible in the game. Just before meeting Legion on Reaper ship. Doing it early in the game will always result in failure as straight resolving dispute (excluding possible later option to convince either side) requires exceptionally high paragon/renegade score.
Thessian is right up to the point that you need a high Para/Rene-Score. But this has nothing to do with your blue/red bar. It is the ratio of the possible P/R Points you could have gained up to this point each mission/conversation and the ones you actually aquired.
Say you need a Score of 80 percent...
16 points of 20 available is the same Score as 320 out of 400.
Of course delaying this decission gives you more room to maneuver as you can pick the wrong choice here and there, or some missions simply give you both... Paragon and Renegade Points.
So a balanced Playstyle will not benefit you here.
I even did the 2 LM right after Horizon, Miranda first, as hers is available instantly and Jacks right afterwards. Combined with a thorough 'Harvest' of your P/R Points and the 100% Boost from your passive Class Ability it is possible to settle their dispute even that early in the Game.
If you are still unsure..... pick up the Death Mask from Ratch on Tuchanka. Even 10% RepScore Boost can make a difference.
As for the Suicide Mission:
Against all odds Miranda can only die, if she is unloyal and
- in your Squad during the Final Fight (definitly dead), or
- Holding the line and your average score here is below 2.0 and she is the only unloyal, as her name is one of the last on the list of possible casualties.
She cannot die in the Vents or as Escort, as she is not assignable for this Job.
Even if Jacob/Thane do the barrier on the long walk, she cannot die, as it will always be the other squadmate, who gets taken by the Seekers... no matter their loyalty.
And she won't die as Fire-Team Leader, even if unloyal.
So if you have Garrus, Zaeed and Grunt loyal and holding the line, leave her with them and she'll be fine.
For trilogy reasons only Miranda should be loyal, except you want a certain outcome.
Have you ever skipped Grissom Academy in ME3?
What do you think?