You have a few options, depending on your space:
Run the wire in a straight line as long as you can. Terminated, this is the classic Beverage antenna (search on this board for prior posts about this antenna, how to feed and terminate it, etc). It will be directional towards the far, terminated end, opposite the feed point end. Left unterminated, it will be directional in both directions. Beverage antennas are typically run 6 or 8 feet above the ground.
Run in a large loop, this is the classic Sky Loop antenna. Make it as large in perimeter and enclosed area as you can. Also search for posts here about this antenna type. A sky loop antenna's directivity is often unpredictable due to many lobes and peaks, especially as you go higher in frequency. With sufficient hand waving, you can assume it is mostly omni directional with those unpredictable variations. Height generally helps improve low angle reception, but even 20 ft will "work".
I have both Beverage and Sky Loop antennas here, they both work well, for different applications. Again, some searching here will turn up many prior posts and discussions.