I would either be Venetian or Outremer, trying to build a successful colleganza trading between Venice and Sidon around the year of our Lord 1150ish.
Trading is probably the best idea in the 1100s, before that its becoming a God-King and trying to speedrun up the tech tree which involves far too much sourcing of materials in order to construct the mechanisms over and over for me. Material-sourcing, processing, and construction just seems so difficult and tiring considering a barbarian invasion could smite my civilization at any time during or after my speedrun. I wouldn't like my chances, even though they aren't that much better in 1120 A.D.
Due to the Pactum Warmundi and The Golden Bull of 1082, Traders made bank very easily because boats were so easily lost at sea that sailors were paid quite well, and being able to speak Outremer French to the Crusader States in order to buy fancy things and sell them in Venice as well as in the duty-free trading ports, exempt from tax, throughout the Byzantine Empire ensures a pattern of growth until I could afford to mine gold in Kremnica. I would work to make a trading family for me and my sons, marrying my daughters into minor Byzantine and Crusader families.
If the trading went well enough, and the gold mine in modern Slovakia but medieval Hungary wasn't possible to innovate or monopolize then I suppose I would probably be stuck modernizing steel-making.
- Strongly heating wood in minimal oxygen to remove all water and volatile constituents in order to readily supply myself with charcoal.
- Burn limestone or seashells, that contain calcium carbonate (CaCO3; mineral calcite) in a lime kiln to make quicklime.
- Build a set of waterwheels to bellow air
- Assemble a blast furnace, where charcoal, raw iron ore, and quicklime are continuously supplied through the top, while a hot blast of air is bellowed into the lower section of the furnace through a series of pipes called tuyeres, so that the chemical reactions take place throughout the furnace as the material falls downward.
- The Pig Iron formed by this is then placed into another furnace constructed to pull bellowed air through tubing (around which an intense fire is made to heat the piped air) and over the iron without any fuel coming into direct contact with the iron, a system generally known as a reverberatory furnace or open hearth furnace.

Maybe I even manufacture a good steel (.8 or .9 Carbon) for weapons which changes history a few degrees. Leave a Venetian palace with a map of the world impossibly behind?