You won't need to "introduce" berries and seeds to your birds....if they are in the area they have already found them.
I find some kinds of suet cakes do better in the summer than others....and of course don't hang it where any sun will hit it.
Robins Doves and Juncos won't eat from a suet feeder.
The best thing you can do to attract birds is to provide a constant water supply....they all need water.

Black-oiled sunflower seed attracts the birds that you mentioned and others, too. The problem with nyjer socks is that the seed gets soaked in the rain and stuck together. A nyjer feeder is much better. Also, you can find suet labeled "no-melt" suet in pet stores as well as Wild Birds Unlimited and other bird stores.

I feed birds all year round but I only feed suet in colder weather. The no-melt suet works but I stop when the suet just gets too unpleasant to handle. I've read that the suet is attractive mostly to birds that eat insects, and insects are plentiful here in warm weather, so I'm not depriving them. Besides, I want the birds to eat insects (mosquitos! ticks! beetles!)

Mixed seed feeders and nyjer feeders stay up all year round and I throw some seed and nuts on the ground for the ground feeders.

Claire

I forgot to mention caterpillars - I really really want the birds to eat caterpillars that defoliate trees.

Claire

To Lindac :
The robins love our feeder! We see a few of them eating the droppings from the ground, then they go on the feeder and eat! This morning I was outside on the porch, and a robin decided to eat 6 feet away from me!

I think I'll simply buy some black oil sunflower seeds to add to the suet I'm going to make, and offer the seed in a seed feeder as well..
During nesting season the parents might be tired and could stop by for suet, and migrants could as well.

i make my own suet here and in cold weather add more lard or shortning but in warm weather molasses or sorghum and more peanut butter as binders. and mix in mixed bird seed or cornmeal to make a stiff dough. i get flickers and lewis's woodpeckers nest here in spring and they love the sweet suet mix.

I feed 2 types of suet or lard - the plain raw beef suet in a suet cage, and a home-made mixture of rendered fat (suet or lard) with peanut butter, corn meal and flour, nuts, etc. Rendered suet stays solid at higher temperatures - I think it's in the 90s F - than unrendered suet.

I do feed the raw suet year round and it doesn't melt because we don't get temps in the 90s that often, and also the suet cage is sited on the north side of a large tree trunk so it has little sun exposure. The woodpeckers love the raw suet but many other birds will nibble on it too.

Many birds also love the home-made mixture, and the Bluebirds come every winter to eat nuggets. This past winter I had up to 12 bluebirds! But I feed much less of all the bird food in the summer because there are usually plenty of insects for them to eat.

I have four suet feeders here-I use no melt ones in the summer, I get woodpeckers all year long, FLickers and the occasional wren at the suet feeders. all the finches go to the bagged thistle bags and the one thistle plastic feeder. Juncos in the winter go to the metal thistle feeder I put out. I also have safflower seed in a tube feeder front and back for the cardinals and occasional woodpecker??, A house seed feeder with a pressure bar to keep the squirrels out of the feeder. And lastly I throw mixed seed on the ground in a small area to feed the Jays and sparrows. Costly but worth it. In the winter I throw out black oil seed.

Well, my last store bought suet melted, I'll have to make some tommorow..
I think I'll keep on feeding suet..The cardinals,robins,blue jays and even a house finch seem to be enjoying it..And I'm the only feeder in the neighborhood..

I really like this feeder, but the blog it doesn't seem to say where I can buy it (online or in my town) :
http://wildbirdsunlimited.typepad.com/the_zen_birdfeeder/2011/12/looks-coolbirds-love-it.html