There are several things you can do with National Advantages.
You can search this forum for posts with "National Advantage" and read the many thoughts here.
You can utilize the Larry Harris Tournament Rules v2.0 NAs.http://daak.de/regeln/eng/AAR_LHTR_v2.0.pdf
Don't get hung up on the name, these rules are used by many, if not all online clubs. I would recommend these rules, if you are still using the out of the box rules, there are flaws that LHTR corrects.
Personally, I utilize a rules set that has created their own National Advantages that are balanced. There are many house rules/variant available, I don't want to go too much into this or I'll get slapped for posting in the wrong forum. The link I would refer you to is the Enhanced rules set: http://www.axisandallies.org/forums/index.php?topic=11203.0
You can just utilize these National Advantages if you'd like. Once you get those down and you are looking for even more strategic options than Revised offers, I'd recommend these Enhanced rules (shameless plug!)