The obvious answer is: whatever they could get. Despite certain media driven stereotypes, the buying and selling of labor through wages was a common feature of the Roman economy--it is simply not true that all the work was done by slaves, and the free constituted an idle mob on the dole. There was even something like a conception of labor policy and employment: there is a story in Suetonius (Vespasian, 18) to that effect:

To a mechanical engineer, who promised to transport some heavy columns to the Capitol at small expense, he gave no mean reward for his invention, but refused to make use of it, saying: "You must let me feed my poor commons."

There are plenty of reasons to doubt the specifics of that story, not the least of which is that the Romans did make use of labor saving machines and it has a general fable quality to it, but it does nicely illustrate that there was a connection between subsistence and employment, and that big projects requiring lots of labor might also provide opportunity for large masses of people (although it is worth noting that Rome was a city of perhaps a million people, so these projects would still be fairly marginal).

On a more specific level, there is a fairly decent amount of what we can call "wage data"--although it is not really wage data to modern standards, more just references to how much a particular person was paid on a particular day for particular work, not anything like average wages across a sector. Perhaps the closest thing to that would be the price edict of Diocletian, section VII of which gives the prices for labor. Leaving aside the actual wages, you can see plenty of examples of the sorts of things people would do for wages, from a barber (two denarii per customer) to a wall painter (75 denarii a day) to a water carrier (25 denarii a day). It is actually kind of a fun list to go down, and see that, oh yeah, they would consider the labor to bleach or color a new women's tunic (16 denarii per unit) to be different than bleaching or coloring a used tunic (10 denarii), or that figural painting (150) specialized labor, and earned more than general wall painting. And that "guard for the clothes in a public bath" was a job one could have.

(The actual wage figures are at best estimates, also a denarius in Diocletian's day was not the same thing as a denarius in Augustus', but it is still an interesting example of "ideal types")