For anyone going to the Czartoryskich Museum in Krakow, we were just there this morning. It's a very interesting museum with a lot to see but also somewhat confusing so here's some hopefully helpful info that may save you some time (and aggravation?). Let's start with the entry.
There is no signage saying what to do if you already have tickets or anyone to guide you ... unlike many other places that have a line for those with tickets and another line for those who need tickets, there's just one long line for everyone. If you're entry time is close, don't wait in the long line ... squeeze past those waiting at the small entry and work your way to the front where security opens a door to let a few in to purchase tickets. Try to get one of the guards attention and hopefully he will come over, or just wait until the next group is let in. Show him you already have a ticket (best if have a printed copy) and he should let you go inside. After entry, the right side has 2 lines ... first is to go in, second is to store your backpack before you get to go in.
If you're there to just see the da Vinci and/or maybe a few other pieces and don't know where you're going or have a map, ask one of the staff inside for assistance (they were all very nice and helpful). There is no map or signage where things are, just a small plaque with a room number on the floor as you enter a room. Nothing that tells you what's where (at least I didn't see anything) nor did I see anyone with a paper map of the museum. If you're there to see da Vinci's Lady with an Ermine, go to floor 2 and work your way to room #7 ... but first stop in room #6 for Rembrandt's Landscape with the Good Samaritan. That's two out of my four must-see items checked off ... and praise be the final 2 are right there in the next room (#8) ... Chopin's death mask and the urn with the remains of Copernicus. If I had a map I could have found them quickly and had more time to see some of the many other worthwhile objects in the museum but time was now short before our next stop so we had to leave. Hope this helps someone save some time and stress.