Conservative economist Milton Friedman endorsed the idea of a basic guaranteed income in the form of a negative income tax.
You should watch the video, but to sum up: under this scheme, you set a "floor" below which people receive supplements to their income, either on their paychecks (if working) or directly (if unemployed). You also set a rate to apply to the difference between earned income and the floor, which supplies the amount of the supplement.
For example if your "floor" is $40,000 annually and your rate is 50%, then a person earning $20,000/year would also receive 50% of the difference in supplemental cash, in this case $10,000 over the course of a year.