Try to put the feeder under a tall canopy or close to cover. If it is easily seen from the sky it will become a Hawk feeder. They love to swoop in and pic woodpeckers right off the suit. Once they know where the free meal is they will stick around. I learned the hard way. Now mine are under cover.

Also, don't put it near bushes or other areas where cats can ambush them. I learned the hard way too.

So the best place is on the trunk of a tree that has a good canopy above it, but is pretty open below/around it. My suet feeder is now in such a location and I haven't had another casualty (knock on wood).

It may be my imagination, but I think maybe the birds can tell it's in a safer location too. I seem to get more customers since I moved it.

I think it is easier to get a bird to a suet feeder if other birds are already feeding at a seed feeder nearby. Once birds are hitting at the seeds they check our what else may be available. I have several suet feeders, one that holds the suet inside a cage allowing the little bush tits to feast without fear of larger birds, a standard wire suet feeder, and a feeder with a tail board for the wood peckers. I will say that the wood peckers use all the suet feeders,but do use the tail board for balance when available. I have tried many different suet types but think that the peanut butter with insects, (YUM), is the type most consistently favored by a variety of birds. Of course, you then have to deal with squirrels. We have red shafted flickers, and downy wood peckers at the suet feeders. I also have a piliated woodpecker that visits my yard in the late winter, but doesn't go near the feeders.