Despite some ups and downs in recent years, real estate continues to be a preferred choice for investors who want to generate long-term returns. Investing in a rental property, for example, is one way to produce a regular source of income. At the outset, an investor may be required to put up a 20% down payment to buy the property, but that may not be a barrier for someone who's already saving regularly. Once reliable tenants are installed, there's very little left to do except wait for the rent checks to begin rolling in.
First, ask yourself if your app idea is feasible. Will it make money? This information is completely free and available on every single app store. Browse the “Top Grossing” section of any category. Check the rankings. These rankings show you the market demand. It’s not rocket science, but this isn’t the first step that most people take. Do you already see your app idea? Don’t be discouraged if you do. This is the best way to see and know if that idea is making money. If your app idea is ranked in the top grossing, even better. Do you see less than 5 version of that app idea? Then you have a good shot in this market!
Some retirees start consulting businesses, do handy-man work, or in some other way become self-employed. Many are caught off guard by the payroll/FICA tax and can get behind on taxes once they become self-employed. If you become self-employed be sure to work with a good tax professional who can help you calculate the right amount of payroll tax to send in, otherwise April 15th will be a very unpleasant time of year for you. 
Alright few of them are okay but not all of them are abble to get money if you are not in USA and well Im not so its kinda bad that its not possible to do it. I dont know so far Im new at this but I have heard so far that FluzFluz is okay I dont know exact numbers how much you can get it but I like the Idea that you can get the money from purchases and as well from others so If someone is interested you can check it out maybe you will find it interseting.
When a taxpayer records a loss on a passive activity, only passive activity profits can have their deductions offset instead of the income as a whole. It would be considered prudent for a person to ensure all the passive activities were classified that way so they can make the most of the tax deduction. These deductions are allocated for the next tax year and are applied in a reasonable manner that takes into account the next year's earnings or losses.
Investing in real estate has been around for ages.  Whether you are looking to buy your first duplex or getting into a large commercial property, rental properties can provide passive income through rents with some very appealing tax benefits.  This method can be harder to get started with given the initial capital needed in most cases, but is certainly a great way to generate passive income.
One of the most appealing options, particularly for millennials, would be #12 on your list (create a Blog/Youtube channel). The videos can be about anything that interests you, from your daily makeup routine (with affiliate links to the products you use), recipes (what you eat each day) or as you mention, instructional videos (again with affiliate links to the products you use). Once you gain a large following and viewership, you can earn via Adsense on YouTube.