@OlivieroRuggieri Hi Oliviero,
I am anything but an expert player but i have played around 8 games of North Africa at this point (6 playing the axis vs a friend, and 2 vs myself) so i feel like i can give you some of my findings at least.
As the axis, using the known ITA - GER Can opener from global is always a good bet, attack with italy first, Tanks, inf and arty supported by planes (preferably bombers), after that use german tanks with mechanized inf + planes to finish the job. this works best before round 7 since the us hasnt joined yet and cant counter in between the turns of ITA and GER. You also have to try to keep supplies from getting to malta if you can, the 15 ipcs the uk gets can really hurt in the long run, even more so if they get it multiple round.
Now as for allies im not that experienced as i have mostly played axis, but i can tell you this, use the 12 ipc starting reinforcements to get a mix of ind/arty/AT/tanks, i dont know if there is a optimal setup but tank + arty/AT + inf makes a nice 12. In my experience it is your best bet to try to get navy control of the med, to protect malta or to disrupt convoys. So first round UK i would buy a battleship + either 2 destroyers or battleship + 1 destroyer and a sub, spawn them at gibraltar and round 2 you can combine them with you starting navy in the malta convoy zone. Put down some sea mines and try to get 2 fighters in malta the convoy zone to really lock it down. The axis can still try to contest it if they really try but 2 battleships + 3 destroyers + 1/2 fighters + sea mines should be quite a deterrent
You also want to be trying to put as many land mines down as possible, on tobruk, bengazi, mersa matruh and cairo, in the Rommel scenario the uk will be under immense pressure and you have to survive until round 7. Focus on mining cairo every turn. Also try using you starting scout jeeps to destroy as much axis supply as you can, dont use them on 1 territory but try to spread them out and maybe even kill a plane if you get lucky rolls
As for unit efficiency, inf is always good, the matilda seems really cost effecive (5 ipc for a 5 def 4 attack is pretty nice) the downside is they get 1 movement so no blitzing or cheeky flanks. Ive played a game as the axis vs a matilda spam and it was not that nice. If you combine them with some meat shield like inf or arty/AT you get a nice defensive force with the means to counter attack.
Those are all the things i could think of right now, hope it helps you in your coming games.
Good luck and let me know how it goes.