Without knowing much about your living set-up, and assuming you already have decent shelving...
1: Sell any doubles and packaged ones first, as they're extraneous and/or space-intensive.
2: If you don't have doubles or packaged ones, try displaying them in whatever mode takes up the least space. If you own your own home you can also put small hooks in the ceiling and have the fliers in flight, assuming the missus/hubby lets you. It's easier if you have your own room too.
3: Pack most of the rest up, keep 'em in boxes, and just have a few 'on the go' at any one time. This is also a good idea for keeping the non-TF-supporting missus/hubby happier about your collecting as it's not so 'in their face', and can make hiding new acquisitions easier.