What is the highest amount of lift I could go with a early nintys s10 blazer without having problems with u-joints or driveability? And also what size tires would you recomend with the bigest lift I could go without messing up stuff.

 

Highest lift you can go depends totally on you. Your fabrication skills and pocket book.
I am going to guess you want to keep the IFS front end, in that case I highly recommend a suspension lift kit. Most run around $1,300-$1,500, plus installation costs. Depending on the lift kit, you can run either 32" or 33" tires. I would not go any bigger then 33" tires on the stock axles, and even 33" are a strech if your into serious wheeling. For a street queen, 33" are fine, however you should also replace your gears in each axle, that can add another $1000 to the project, although it will save a $1,500 tranny.

Less costly options.
30" tires will fit on the factory wheels and fit without rubbing anywhere.
31" tires will fit with a 2" lift, either body lift kit or suspension lift kit and run the factory wheels.

Now if your going with after market wheels, you have to be very carefull with the backspacing. I had trouble running LT235/75R15 (29") tires on 2wdr S10 wheels on my 4x4 S10-Blazer. The front tires would rub on the rear of the fender. With 4x4 wheels I can run 30" tires on the same truck and no rubbing. I think the 2wdr wheels have about 1" to 1-1/2" less backspacing.