I use an E-Reader and use the 10-Up card

EZ way
World 7 Fortress

1) Make sure you are Super Mario or better(If you aren't, there's a mushroom in the room after the room you start in).

2) Bust up the fourth row of blocks in the part of the stage that has a platform sticking out of it. You should get a P-switch.

3) Stomp it, and collect all those coins that the blocks turn into.

4) When the coins turn back into blocks, exit through the door on the ground and reenter, the blocks will be reset! Keep doing this until the time runs out, then reenter the area and repeat.

Using this strategy, you should be able to get at least 9 ups every time!

yes that is a good way, But...

if you beat the fortress you can't go back there to redo it

I'm not saying you have to beat the fortress, but just get ups until the time runs out

I think a lot of people know this already, but I'll explain it here because I did not see it posted. In world 1, level 2 (note: you need to have the leaf to do this), the second tunnel (the high one) where the goombas are coming out three at a time, get on the top of the tunnel and jump down using your tail to slow down the falling process, aim for the goombas that are down there (I suggest you aim for the one with the wing first). While stepping on one, hold the "A" button so that you will do a high jump. Once up in the air, use your tail to slow down the falling process again (note: the slower you do this, the better because that gives time for more goombas to come out of the tunnel). Simply repeat the process and you'll earn a lot of ups. If you mess up, you could always do it over again by entering the tunnel that is not too far from it, then come back to step on more goombas. I like getting ups this way because you could do it all the time until you die, and it really helps you because you're on the first world only. I got like 40 ups each time I do it.