we will be cruising in nov. and have realized that we will need to board a tender to get to our shore excursions, what is the general rule about(if any) leaving the ship or do you just have to line up the earliest & wait?

Is your shore excursion booked through the cruise line? Or did you set it up independently?

The tender holds approximately 50-75 people and you just show up on the disembarking deck and board. The most you may have to wait for one is 15 minutes as all they do is make continuous round trips all day. I've never encountered a crowd where it's already full and you must wait for the next one (but I'm use to smaller ships so maybe this could happen on one of the larger ships).
It's very EZ.

On some ships it is a pain in the butt. If you want to get off early you have to go and get a ticket with a number. You then hang around until your number is called. Depending on the size of the ship it can take up to an hour.

It all depends on the size of the ship you are taking. If you are on one of the mega-ships like Princess, you need to report to the lounge, take a number, and wait for your turn. You will not get on a tender till all the tours have left. If you are on an excursion, you report to another lounge, get a sticker and wait for your number to be called. Yes, it could take an hour. If you are on a luxuary ship with fewer passengers, there's no line. You just show up whenever you feel like, and get on. Getting 2,00+ passengers takes much longer than getting 3-400 people off the ship naturally.

Lucky you. Boarding a tender can be fun. I assume that you are travelling with a crew that knows how to organize to disembark passengers efficiently. Yes, you might have to wait your turn. So what? You'll be in a comfortable place, surrounded by vacationing people with interesting stories. Go to the bathroom, grab a water bottle and follow the usually well described proceedures. Put on a happy face, consider the louge full of people as part of your cruise experience and stay in your moment. Enjoy the ride!

thanks friendy cruisers for all for the info, we will be on the star princess(hopefully it won't be filled to capacity) and haven't decided on what excusions to take yet. not sure about booking on the cruise line or other sources. seems the more info we receive the harder it gets, but i guess that's part of the fun.

Tenders are a piece of cake. I've always just walked right on (OK maybe I waited 5 minutes for the tender to return back to the ship). I've never had the experience of taking a number or waiting around in a room for 45 minutes to an hour as others are relating...What ships do this so I can be sure to avoid them?
Hopefully you'll just walk right on.