The first 10 must be built in C3 Countries, after that you look for countries with PC Presidents. After 40 game months you can move your first 10. Ideally you want Premium PC Presidents for the stability, however you want primarily high welfare and low tax countries that can support your employment needs. If you are impatient, there is always Roving Eye's countries generally low tax. You also have to upgrade your Corps, mine do it automatically via the settings. It does take some time, but you should be able to afford the deficit with your start-up Enterprise cash. When you can, move corporations whose employment drops from 100% or bump the Salary up if the country is not losing its PC President. On salary, if country is losing a President a higher salary will not really benefit you, they be losing Population. For me, I simply move the Corp if I figure it pointless to play with salary. In a country without a PC President you are likely losing employees because a new corp is coming in and the country lacks the employees to fill everyone. Can't be helped. Hence PC countries tend to be better in that regard, but not always.
Just keep building new corporations that have consistent trade deficits. The income will eventually follow. I usually take a break and let my income adjust after about 15-20 new corporations in a new Enterprise. That way I don't have to kick much, if any, cash to it. Then I build a few more. You will have to gauge what is sustainable for you. Figure about 40-45 billion SC$ start-up cash per corporation. I don't remember exact numbers there, but you will see it in your finances. New corps do cost money and so does the wait for them to be profitable. It will take a little time, but you will be making decent cash pretty quick.
A note on bumping salaries. I usually do about 20-30% higher than the PC President if I am forced to bump it. They generally have one salary and multiple Corps. That should suffice. At other times when the President has a 400+ salary I look for 2-3 Enterprise owned corporations with close salaries and do 20-30 higher. I generally never go above 350-375%. If I have to, I just move the corp or let it sit and not bother with it. Except Air Transport. Those I peg to about 450%, because they cannot be moved.
A note on loans. In the beginning, I let Corps get to about 90 billion SC$ in loans before I took steps and closed them down. However now, I just simply close them. I don't normally close corps unless they are in debt or about to go in debt. Your private Corps will suck your cash before going in debt, especially new ones. I generally ignore them in the beginning.
I have probably forgot a bunch of things...