Michael,
Antennas can certainly be fun to make, and less expensive than buying a ready made one. But as you are finding out, there are a few things you really do need to know about antennas in general, and of course for specific antennas.
To start with, an antenna is a conductor of electricity (RF is just another form of AC). It it will conduct electricity then it can usually be used as an antenna. that means that wire, metal tubing, whatever, are possible sources of that 'conductor' you'll need. Pick the one you are most comfortable in using, that will either hold it's self up or can be help up in some manner.
For instance.
Wire antennas, dipoles, are typically a 1/2 wave length in length. So, select a wire that's strong enough to hold it's self and maybe the feed line up in the air. So strength is one characteristic that's important. If it has a huge amount of resistance it probably isn't gonna be a very good antenna. Ordinary copper, aluminum, steel, etc, doesn't have a huge amount of resistance per foot so are usually nice stuff to make antennas from. Small differences, like between copper and steel, just isn't a biggy. Another aspect is just how hard is this wire going to be to work with? If you can't bend it by hand it'll be harder to work with, right? Doesn't mean it's 'bad' wire, just harder to handle. How about insulated wire? It'll work just fine in most cases, and the color of that insulation can be of benefit too (hides it?). Just how 'hard' is that wire? Does it stretch? That's not so good, but it's manageable. Just don't stretch it too far!
All antennas have two 'poles', call them (+) and (-) for convenience. RF is alternating current so those poles do switch every half cycle, so just be aware of that. The center conductor of coax goes to one pole, the braid of that coax goes to the other pole. One way of doing that connecting is by using an insulator between those two poles, or sides of a dipole and just soldering the coax conductors, one to each side. Another way is by using coax connectors, PL-259 is the 'male', an SO-239 is the 'female' connector. Put that SO-239 in/on that center insulator separating the two 'sides' of that dipole, make appropriate connections. (Nothing so far that you already don't know or at least have seen, right?)
Which of those two ways is 'better'? The one that's easiest for you to do -correctly- is the 'best' for you. They will both work the same. Lot's of 'pros/cons' about that, but they both work just dandy.
There's more to making antennas than that, but that's a bare-bones description. There are quite a few sites that can give you more information, just 'google' for them. @#$ near anything can be 'improved', so making changes is normal as you can get. (Just remember how things were before so you canchange back if that 'improvement' isn't what you thought it was, you know?)
Have fun.
- 'Doc