Some steps I recommend:
Pre-attack option is to adjust HQ Target and HQ location appropriately, but that can lead to AI Japanese getting hint what you are doing and bringing in something nasty, like multiple CV TF in 1942..ouch
Start with using SIGINT about Army and Air units in location. Then start to build up invasion force:
1. Bring in Carrier TF first, bring 2 CV TFs if you can. Bring in BIG CV TFs, never use TF with less than equivivalent of 3 CVs in one TF as allied. You need maximum CAP against Japanese in 1942-43. In 1944 you *may* pull through with superior training and planes with 2. When preparing location for invasion, use Move Option (1-2 is OK)-Commander's Decision-Land Units. If you have 2 CV TFs, latter may have option to target TFs, if you worry about enemy CVs. (And if you do, it may be better not to invade, but provoke Carrier battle in first place).
Always have Admirals with best possible combination of Air and Agressiveness ratings commanding your CV TFs. Get Halsey and give him a TF. And don't bother with CVE TFs, use them to chew up bases you have bypassed and isolated. CVE TFs are toast if against serious enemy opposition.
2. Bring in Surface Combat/Bombardment TF. Bring 2
3. Invasion Transport TF, single one (Cargo TF is not doing good for you). Composition depends of range from loading point to landing point. CLs, DDs, APDs, APs if long range, needing faster ships. Load those fast APDs with supply, not with combat troops, they cannot carry much men anyway..and you are going to need that supply on beach. If short range, you can add MCS loaded with supply or substitute APDs with MCS. And anyhow, don't spread you troops too much, if TF has excessive APs, load them with supply. MCS are slow, speed is life. Invasion TF commander should be (this I cannot swear to be true, but it seems so) Admiral with good *LAND* and agressiveness rating. (Don't bother with naval rating, they are toast if meeting enemy Surface or Air TF anyway.) This seems to help with first wave combat where you cannot choose a land leader, and is especially critical with combat on atolls where "only one walks away". And never attack anything without overwhelming odds. 2+ divisions is good mostly, preferably 80+ exp. They'll get trained
4. Follow on supply TF, don't bother this with atolls, they arrive after either side has been evacuated of eliminated. If, however, your troops get beachead, but fail to take the base, this is useful to get them back to fight.
And ALWAYS assign good Leader to any important TFs..and pay attention to what kind of ratings those guys on higher HQs have..and change HQ leader and Air leader appropriately. They don't need to be stellar, but decent, when commanding areas of your main thrust.
Any ideas/comments ? I think there is lot of things to debate
Cheers,
M.S.

