The minute you put up a feeder, you WILL see squirrels, that said, it’s not that big of a deal. The easiest thing is a suet cage and a couple of cakes for the birds to come eat, seems to last the longest too so that’s my vote.
The Bluejays can be basty little nastards, but Cardinals hold their own just fine. Sunflower seeds are their preferred food in my experience, you can buy big bags fairly inexpensively, the mixed stuff will pull in more little birds as a lot of them go for the finer meal. There will be seeds and shells in about a 5ft radius of the feeder, regardless of the style you go with. If you don’t care about squirrels, hang one from a tree, if you do, get a post mounted one and grease the pole. That’s about it for my advise. I found I’m too damn lazy to fill the thing daily so I opted out years ago.