I probably could have made a living as a bullshit artist. (AKA A Philosopher)
Failing that, Thief. Can you imagine how easy it used to be, to be a thief in a major Medieval city? No real guns, roof-friendly city design. No serial numbers. No cameras. No photos. No IDs. No forensics. No real high-speed communication.
Of course, there were no lethal force restraints either, but I guess you kind of accepted that as part of the bargain.
It almost sounds as though you think that second would be a good idea.
You realize that there was rampant poverty at that time? And a lot of people back then turned to thievery? You wouldn't be anywhere near as skilled or experienced as your "friends", and the populace would be prepared for your efforts. You should expect light sleepers, screaming being answered quickly, and people reacting with deadly force. They will draw daggers in many cases, but in a place where they lack such tools, the mob will manhandle you out into the open to exact a revenge (at worst lynching, at least losing something important).
The absence of the securities we know today would not mean the absence of security.
As to being a philosopher, how many heretics can you think of that were successful? How many would you guess weren't? Cults, when the christian one was rising in power, were a dime a dozen.
I'd probably end up being someone's servant. If I were lucky, I'd occasionally have enough time and money for a book or two. In a post-industrial age but pre-substantial women's lib, I'd probably be doing factory work... and in a rural area, married with nine children.
If I were either male or could do a good enough job faking masculinity, I'd probably go straight for the priesthood (assuming medieval/pre-renaissance era). For a long time, monasteries served to store human knowledge, and priests were educated to carry on the mental constructs of a civilization. After becoming a priest, I'd go rediscover the scientific method, steam power, electricity, and the computational engine. Erm, if I could remember my basic high school education at that point, that is...
I don't think that guess is right either. Hm, perhaps we should start from the beginning, and correct it as it goes along.
You appear in a random location nearby or in civilization (but out of view), probably with the sound of displaced air and a couple feet off the ground. There are numerous times you could be in (age, year, season, night or day), but you will probably be unable to identify this at beginning (assuming you know you've been time shifted). We will assume you are stark naked at this point (since common items today would give you advantages far beyond your intelligence and choices, and choosing what you get would be a pain), with the exact same health and mind you have now.
If it is cold (depending on time and location) you will die of exposure quickly or eventually, and must beg safety at the (nearest) civilized buildings (If it's warm, you will have more options). Your feet might be bleeding by the time you get there, or freezing if there's snow or frost. At which point the current time and place will matter even more, as some value hospitality, and others value slaves (in varying forms). You will probably be totally unable to understand each other, but since you are both human, you should be able to understand very basic things quickly. You should also remember, that you are quite probably taller than they are, and look different; more so the farther back you are.
Let's limit the time to the last 2200 years before 1510, so we have material to work with, and exclude the places without known organization at the
chosen time.