How to fix your country's economy:
Part 1: Vital Infrastructure
You need a high education index to ensure an adequate supply of workers. In theory, you would think that an education index of 100 would be sufficient, because you would be training exactly as many workers as you needed.
However, in practice you need a much higher education index, in order to train many MORE workers than you actually need. This is because the labor market in simcountry fluctuates constantly, and you never know for certain which types workers you may need more of at any given time. You should always try to maintain an education index of AT LEAST 200. With an education index as low as your country has, your country is at risk of frequent shortages in various worker groups.
Also, because the simcountry labor market fluctuates constantly, you therefore need to regularly update your country's education priorities. However, you also need to be aware that it takes approximately one real-life day for your country's education priorities to fully adjust. Therefore, it is best to inspect your country's education priorities once each day at a regular time everyday, updating them if necessary, but not to constantly tinker with them numerous times throughout the day.
As for your transportation index, healthcare index and social security index, when you have enough money you can raise them higher than the game recommends. This makes your citizens more content, thus increasing their productivity in corporations.
However, I would not recommend that you do this until your country's income is sufficient to support the cost of maintaining those indexes at a higher level. Until then, I would suggest that you maintain your transportation, healthcare and social security indexes at a level either of 100 or else just barely above 100.
The combination of good education, together with adequate but affordable healthcare, transportation and social security, will give your country the motivated, capable workforce which the corporations in your country depend upon.
Part 2: Private Enterprise
Privately owned corporations are WAY more profitable for states than are state-owned corporations. This is because the rules of simcountry give private corporations very substantial economic advantages over state corporations. This is done SPECIFICALLY in order to ensure that no state in simcountry can make as much money from state corporations as it can from private corporations.
If the game managers didn't ensure that private corporations were more profitable for states than state corporations were, most presidents would simply ban private corporations and rely entirely on state corporations, in order to have more control over their countries' economies.
Then, if there weren't enough C3s available to build corporations in, it would be almost impossible to play the game as a CEO. Trust me, even with no corporate profits tax, private corporations are still WAY more profitable for a state than are state corporations. The game managers have done an excellent job of ensuring this.
To attract private corporations, the most important thing you can do is to build up your country's infrastructure as explained in part one. The second most important thing which will make your country attractive to private enterprise is to COMPLETELY ELIMINATE your corporate profits tax. The vast majority of money which a state receives from private corporations comes not in the form of taxes but rather in the form of something called country resource payments.
This refers to the money which private corporations pay every month to your country in exchange for use of the nations resources, such as water and electricity. These payments are usually, although not always, far larger than the monthly profit of a typical state-run OR privately-run corporation, and your country can make far more money each month from these payments than it can from any other source.
Eliminating your corporate profit tax is DEFINITELY the way to go, because the amount of money your country will receive from private corporations in the form of corporate profit taxes is infinitesimal compared to the amount of money which it will receive in the form of country resource payments, and eliminating your corporate profits tax will allow you to attract a much larger number of CEOs to your country, which will more than make up for the income lost by not taxing corporations. It will also allow you to attract far more skilled and experienced CEOs to your country, whose corporations will tend to be more profitable for your country than the corporations of less skilled and less experienced CEOs.
If your country is lucky enough to have no state-run corporations, as well as more private corporations than your country's labor pool can support, you can even forcibly remove the corporations which are paying the least amount of money in country resource payments, in order to create room for other CEOs to establish other corporations in your country which will hopefully be even more profitable for you.
Thus, along with building up your country's vital infrastructure as explained in part 1, you also need to completely eliminate your corporate profits tax. You also need to eliminate all of your state-run corporations, in order to help make room for those private corporations. You should try to sell as many corporations as possible, either by selling shares via international public offerings, or else by encouraging CEOs to bid on them. However, if you can't sell a particular corporation, you should then simply close it in order to get rid of it anyway, because you really don't want any state-run corporations in your state if you can possibly help it.
Private corporations are just so much better! You don't even have to manage them, because other players will manage their own corporations in your country for you. Thus, not only are private corporation far more profitable for a state, but also, they are far less work for the president of that state.
As you are in the process of building up your country's infrastructure as explained in part 1, and as you are in the process of eliminating your state-run corporations, and once you have eliminated your corporate profits tax, you can then start sending in-game messages as many CEOs as possible, advertising your country's 0% tax rate, together with its large supply of educated, motivated, unemployed workers, in order to attract as many CEOs as possible to your country.
There is no need to wait until your country already meets all of the criteria listed here before sending invitations to CEOs. In fact, it would probably be best to start inviting CEOs to build corporations in your country as soon as possible, because the money which you will receive from those corporations will be very helpful in developing your country to meet the necessary criteria listed here.
However, if you decide to invite CEOs before your country meets the criteria listed here, be sure to let them know that you are working towards these criteria as fast as possible. That is to say: you are eliminating your corporate profits tax as fast as the game will allow, your are eliminating your state-run corporations as fast as the game will allow, that you are raising your education index and refining your education priorities as fast as the game will allow, and that you will raise your transportation, healthcare and social security indexes as soon as you can afford it.
That way, CEOs will know that your country will be a good investment in the long-term, even if it may be a terrible investment in the short-term. Also, once you start attracting private corporations to your country, be sure to build back to work schools and special clinics, to pump even more workers into the labor force, in order to sustain even more private corporations.