I'm making my own lindy rigs with floats and one bead. I've usually fish with rigs about 30" long. Is it good to make these rigs with longer/shorter snells, and for what conditions should I use different length snells?

Try all different lenghts of leaders. I let two things determine the distance between the sinker and the hook. Shorter leads when the fish are "on" or when the bottom is very snaggy. Longer leads when the fish are off or when the bottom is clean. You will have to find the right combination and it will change each day. Also try putting straight snells behind a bottom bouncer from time to time, it really works great.

One thing that you should try as well - make up some rigs - with no floats.
A few rigs - plain hook only.
A few rigs - a single bead in front of the hook.
A few rigs - with a 2 or 3 beads of different colors in front of the hook.

Especially if you are using a light lindy weight - or a three way rig - you are often better off without any floats. Often, simple is better.

As Steve F - says - don"t drag bottom. Get within a few inches of bottom with the weight - periodiocally drop the rod tip - to insure that you are close to the bottom - but don't drag.

If your lindy snell is fairly long - then you will need to keep your weight higher - to keep the hook from sinking to the bottom.

Remember how far you have been keeping your weight from the bottom. Periodiocally check your bait - if you are picking up moss - mud or other bottom "stuff" raise your weight higher off the bottom. It is obvious that your bait is sinking - and dragging on the bottom.

Keep both your weight and Bait - out of the mud, moss and other bottom junk - and a lot more fish will end up in your livewell.

Take care
REW