Keep the money in a liquid cash fund or T bills. Once you have accumulated USD$50k, move on to invest in Rental property. Based upon your saving rate at the moment, it will take you around 10 years to accumulate this amount along with compounded interest rate assuming that the return is around 3% per annum which can be achieved easily. Repeat the saving rate for the next ten years to save another USD$50k
Use a debt gearing of not more than 50% for your rental property value with a 10 year repayment period. You should have a net return of around 3% per year after paying for taxes, maintainence, etc. Put this money into T Bills or fixed deposit. When you buy your first property, your age should be around 31 years old.
After 10 more years, your age should be around 41. You should have enough to buy two more rental properties with the same debt gearing. Repeat for another 10 years the same process. You will be having three rental properties for rental income at this stage.
When you reach the age of 51, you should have total of three rental properties for rental. All your properties should be fully paid up by now. This means that your net rental income should be around 5%- 8% of your property value. During this period of time, there should be appreciation on your property value depending upon the economic climate. Remember you have fully paid up your property at this stage. Which means you would be looking at USD$300,000 x 5% = USD$15,000 per year of passive income from the age of 51.
From the age of 51, save the USD$300 for earn income into a ten year annuity program assuming that you are still employed. Use the money saved from Properties rental to buy one more property at the same debt gearing of 50% and finish repayment in 10 years. By the time you reach 61, you should have four properties on hand which can easily give you USD$20k- USD$25k income per year excluding your annuity plan. This should be enough for you to retire with a decent lifestyle. With your annuity in place, your monthly income would be around USD$1,200 - USD$1,500.
Remember to purchase a term life insurance if you have dependants so that you create an immediate asset in case some unfortunate incident happen to you. A healthcare insurance will be a must to protect against major illnesses that can potentially cripple you financially. All other types of insurance are not necessary unless you have surplus budget.
Benefit of this plan is that you can leave this portfolio to your Children and help them kick start their life once you leave this world.