Do you have any sort of outside space/yard/garden or do you have a "balcony flat" or similar? If so, you'd probably be able to use the feeders you already have. Some birds (blackbirds for instance) are ground feeders, so prefer to take stuff from that level but will venture on to a bird table if it's big enough.The chances are you'll get pigeons too!
I think it's a mistake to site feeders right in the open, away from places where birds can perch whilst waiting their turn, as it were, and they need to feel safe from predators as well - so if you have any large shrubs it would be a good idea to site any feeders fairly close to that sort of shelter for them. I think you can still get a feeder which can be fixed to a window pane, via a suction pad or two, and these are fine for the smaller agile perching/climbing birds such as blue tits etc.
Perhaps you could take a look at another thread on this board about feeding suet etc to birds, as you'd probably find the info and suggestions useful.