Receive antennas are the easiest thing ever. You just need two things:
- something that conducts electricity
- another thing that conducts electricity
Attach one to the center contact on a BNC connector. Connect another to the shield. Boom, done. If you can't find two things, then one can be the Earth.
Alternately, you can use two ends of one thing that encircles something that permits magnetic fields (like, air).
Until you are approaching a significant fraction of a wavelength (like, 1/4 wavelength), then making either thing bigger will get you more signal. However, once you have enough signal that you are well above your receiver's noise floor, more signal won't make you receive any better: it will just give you louder noise. I'd say, however much space you have, make it that big.
Don't worry about tuning, or impedance matching. This also will increase the fraction of the energy received by your antenna coupled to the receiver, but again, once you have enough to overcome the receiver's noise, more is of absolutely no help. See What is the relationship between SWR and receive performance?
Don't worry about polarization. At HF most of your signals will arrive via the ionosphere which is constantly swirling and changing the polarization of received signals. Whatever polarization you pick, it will be the wrong one in 30 seconds, so don't worry about it.
If you really must worry about something, worry about getting your antenna away from noise sources. Your house, being full of all varieties of noisy digital electronics, is very noisy. If you can get an antenna away from these things, that's good. You must also take care to avoid making the feedline part of the antenna. See Using a balun with a resonant dipole Although that question asks about resonant dipoles, the answers apply to any type of antenna.