As a HoI veteran since HoI 2 I can definately give you some good starter tips.
First off I'd recommend you to watch a couple of lets plays by veteran players.
I like Benjamin Magnus:
https://www.youtube.com/watch?v=VyCL1LIESR8
I'd also recommend any beginner to start with Germany. It's still a daunting game, but with germany you have a couple of things going for you:
Good production base, one single country (no colonies and stuff all over the world) and a government that lets you do what you want.
Japan is actually quite hard. You have little resources and need to balance army, navy and airforce to be effective.
Whenever I start a new game with germany here's what I do.
1) Choose your national focus. I like to build things up so I start with foci that give me industry and resources (start with Rhineland). After that work towards your 5th research slot, you need it.
2) Choose your ministers. As your Political Power grows you can change advisors and laws. I usually try to get my mobilization up so that I can use more of my civillian industry for the country. I also try to get a minister that increases construction speed for civilian factories. Lastly I look for an advisor that gives me land army tradition so that I can change my division templates.
3) Build factories. First some extra civilian factories, after that military factories (and maybe dockyards for building them Tirpitz and Bismarcks).
4) Research: start with techs that increase your industrial base and increase research speed. After that try to chose national foci that give you boni for certain researches and try to research only techs that you have a bonus for. You really need to give your artillery, tanks, small arms and land doctrine priority IMO. I also make sure my fighters are allways up to date.
5) Production: You need tanks, artillery, planes, trucks, small arms and support equipment in abundance so build those. Make sure you switch to newer models when they become available.
6) When you have sufficient military tradition (it's not called that, but I can't think of the correct term atm) update your land divisions. I usually add support artillery, field hospitals, engineers and recon to my main intrantry. I upgrade the reserve divisions to full divisions as soon as possible. Avoid making your divisions to large, when that happens they become less effective in battle. There's this stat called 'front width' or something try to keep that at 20 max. That way divisions dont 'get in eachothers way' during battles.
7) Combined arms: Use your intrantry to pin enemy armies in combat. Bomb them with close air support and make sure you have air superiority. At the same time surround them with fast motorized/mechanized infantry units or tanks. Surrounded units will start running short on supplies and fight less effective. Also enemy divisions that have no where to run are captured/destroyed when they break, meaning your enemies loses way more troops than when you had to shoot all of them in prolonged battles. You've fought the Chinese so you know what I'm talking about
8) Strategy. Don't be dumb, don't repeat Adolfs mistakes. I usually try to keep the sovjets my friends for as long as possible (not too long, because you won't be able to defeat them if they grow to their full potential). Finish France, Benelux and Denmark (to lock off the Baltic sea) and then prepare a naval invasion of Great Brittain. You need air superiority over the English Channel and enough of a fleet to keep the Royal Navy busy while you land troops. The English are usually to busy with their precious empire to properly defend the home islands so a relatively small force (with enough air support) should be able to send Churchill running for Canada. After that you fight the Red Bear and fortify the coast against the Eagle boys.
9) You have 'allies'. Yay. Japan usually overextends like an idiot. Best thing you can do to help them is make sure the Britts are out of the fight and the American Navy is having a hard time in the Atlantic. Italy either powerhouses its way through north africa and the middle east of gets all their transports sunk in the mediterenean. In order to help them you make sure that France and Brittain fall. After that you really need to help the AI by capturing gibraltar (and maybe Malta). Once you've taken gibraltar and Italy has taken Suez the mediterenean fleets will lose supply and make for easy targets for your StuKas.
If the game 'clicks' with you... prepare for endless nights capturing the world.
Also, make sure you check out mods after some clean playthroughs, there's some real gems out there (Kaiserreich, the Great War, Black Ice).
Biggest post I've made in some time
