As there are no guides for this, I will add one with a few useful pointers that I wish I had known from the beginning. Please let me know if you have any feedback or suggestions and I will gladly add them here.
1. There are total 157 side-ops. The ones marked in yellow are story-related side-ops and will unlock as you progress. Complete these as soon as they appear so that you have a smooth transition in the storyline. They will help unlock further side-ops or missions.
2. A tick mark against a side-op indicates it was completed already. However, a white (or yellow) dot indicates that the side-op is playable (or replayable). If you have no fresh side-ops unlocked, it means that the side-ops next-in-line to be unlocked are overlapping with the replayable side-ops. Just play a few replayable side-ops (with a white dot and a tick mark) to help unlock fresh side-ops in that area of operation.
3. Replayable side-ops don't give any special benefits other than mining GMP. So if you don't want the extra GMP and have other fresh side-ops unlocked, just go for the fresh ones to save time.
4. If you are in free-roam and want to save time, choose your side-ops such that they can all be reached using "delivery points" or are around them. It will also be useful to use EMM-mines to disable service trucks that frequently visit your area of operation before proceeding further because they can surprise you at odd times. They will be normally leaving or arriving at the area of operation near the time when you are dropped at a delivery point. Also, in Africa, be careful about rain while inside a cardboard box (or develop water resistant ones, but that's a long shot).
5. As you complete "Eliminate Tank/Armored Vehicle Unit" Side-ops, in later stages, they will have more capable tanks/armored vehicles and enemy gunships. I recommend developing CGM25 rocket launcher from the get-go so that by this time you would have developed a very potent version of CGM25 (level 5-6) that can one-shot the red gunships. Also, I recommend going to the perimeter of the side-op area (purplish blue circle on the map) and gunning down the gunship first. This will make them send a search party to your last known location. Then you can use stun-arm to incapacitate the entire search party (3-4 soldiers) away from tanks/armored vehicles/snipers. This will save you a lot of time.
6. In the later stages, a lot of side-ops will need you to clear puppet soldiers. They are very easy and would just need CQC. So you can have a very light load-out and save some GMP. Also, stun-arm doesn't work on puppet soldiers.
7. Dying immediately after completing a side-op would still count as a completed side-op and you will start again from last know check-point. You can abuse this to your benefit and save ammo and health, especially while extracting highly-skilled soldiers or prisoners from tricky places like OKB Zero.
8. Regarding Side-op 150 (story-related Spoilers ahead):
This story-related side-op will unlock at the fag end of the game near mission 43, and completing it will
. Also, you should not
use the Butterfly insignia in your Motherbase emblem design. Know that
and is a very frustrating mission and it will take some time to develop a strategy to defeat it. As there won't be any
, you will have the same weapons on you as what you had during Side-op 150. But you can always supply-drop whatever you want. Also,
in your remaining missions and side-ops.
Hope everyone has fun completing this one.