Each lens has a minimum focus distance. If that minimum distance is too big, you will not be able to focus the lens when you are close up.
A "macro" lens will have a shorter minimum focus distance so you can get much closer.
There are a lot of lenses that say "macro" on them but are not true macro lenses. True macro is defined as 1:1 ratio. That is the size of the object will be true size on the negative. You may not need that kind of magnification for most of what you plan to do...so you might be able to get away with a "less than true" macro lens.
Check the specs for a lens you plan to buy. You should be able to find out the macro ratio or the minimum focus distance. You may have to check with the manufacturer though.
Extension tube might be a good option. They don't degrade the image quality because they don't have any glass in them. They simply allow you to mount the lens farther away from the focal plane...thus increasing the magnification.
Close-up filters (or diopter lenses) are probably the least expensive. You just screw them to the front of a lens to increase the magnification. They usually come in sets and can be stacked to even further increase the magnification. They do degrade the image quality and the cheaper they are...the worse they will be. They are so much cheaper than a real macro lens that they are worth while.
Also, technique is important in macro photography. A tripod is a huge help, also a remote shutter release is good too. The depth of field will be very narrow so you will want to stop down the lens to maximize your DOF. Serious macro photographers will use a rail to mount the camera on. This way they can adjust the camera position precisely to focus rather than the focus on the lens.