Pint pouring from taps - hold the glass at as much of an angle as you can. If your boss is like any I’ve ever had, he or she will not be happy seeing you pour beer anywhere but the glass. Again, hold the glass at an angle, pull the tap, let the beer pour until the beer is level with the lowest edge of the glass*, then straighten the glass and finish filling. This should give you good head (teehee).
Changing a keg is different depending on the keg, but I’ll say right now, no matter the keg or the system, there will be at least one way to screw up and up end soaked in beer. Get another bartender to show you how NOT to do this. It’s usually grap the handle thing and lift that to the up position, twist, lift off the old keg, find the new keg, put the handle thing back on, twist, THEN move the handle to the down position. Then there’s usually some tubes on the wall with white balls floating in them - follow the line from the keg to that tube, the white ball will be sitting at the bottom of the tube. There’ll be a little plastic thing on the bottom - pull it out, the tube will fill with water, the ball will float to the top, push the plastic thing back in. I know that’s the worst description ever, but I’m only ever heard these things referred to as “things”. As in, "So, you connect this thing to this thing and then thing thing goes here…).
Be charming, but not smarmy. Don’t worry about memorizing 50 or 60 different drinks - there’ll usually be 12 or 15 drinks people will order, and five or so that you’ll be making all night. Know your garnishes (rye drinkers usually don’t like lime, for example), but there’s no accounting for taste so ask and save yourself some time. um, if I think of more I’ll post again!
*(um, that’s not super clear, is it? Okay, so the glass is tilted, and the edge that’s lower, that’s the edge you pour to. Does that make sense?)