Well, it would be best if you could at least go into a store and look at tripods first, before buying.
Be careful about too cheap, too light weight a tripod. They may not be as steady and may not hold up very well.
For macro shooting, you might want a tripod with a reversable column, or at least one that has a lot of adjustability to be used down really low. A lot of macro work is done from a fairly low angle. Look for those features.
Carbon fiber tripods are lighter weight and also have benefit of absorbing fine vibrations to help make for sharper shots. They also are nicer to handle than metal tripods in cold or hot weather. But they tend to be relatively expensive.
Metal tripods are usually aluminum. Look for a fairly well made one with strong cast and machined parts and it will likely serve you for a lifetime. Cheap, thin, stamped steel or aluminum parts just don't hold up. Avoid plastic in many cases. Plastics might be okay for a handle or other minor, unstressed purpose, but not for many other parts of a tripod.
Tripods are sold compete, with both head and a leg set. They are also available separately... legset only and a head to use on them. This allows you to get more exactly what you want and need. For example, you might want a compact ballhead to work with out in the field, but may not be able to find the tripod legs you want with one. They may only come with a pan/tilt head (if they come with a head at all). Neary all better quality tripods use the same size bolt to attach the head to the tripod, so there's a lot of interchangeability possible.
There are also quick release mounting systems. With these, you rather permanently attach a small plate to your camera that fits into a matching platform on the tripod head. One of the most common of these is called the Arca-Swiss system. It has the advantage of being used somewhat universally by many different manufacturers. Other QR systems tend to be proprietary, so you might have trouble finding compatible parts, if ever needed.
For macro shooting, it's often better to focus by moving the entire camera and lens back and forth slightly, rather than trying to focus the lens manually or with autofocus. There are fancy macro focusing stages to do this, which are rather large, heavy and expensive. Or, it's possible to do similar with a longer than usual Arca-Swiss quick release plate serving as a "sliding" rail.
Another consideration is the number of leg sections in a tripod... you can find them with 2, 3, 4, 5 or more. The fewer sections, the better for stability. However, the more sections, the more compact the tripod can fold up to carry around. But, the more sections, the longer it takes to set up, too. Strike a compromise that you feel good about (one of my tripods has 4-section legs, the others are three section).
Tripods without center columns are also steadier. However, without a column the legs of a tripod need to be longer.... And, for macro shooting you are likely to want a center column... ideally one that is reversible and/or possible to use horizontally, in addition to the usual orientation. Just watch that the column and it's mounting mechanism is sturdy and well made (no plastic!). When using the tripod set upright, you might want to try to keep the column retracted, for best steadiness, but that means longer legs to be tall enough for comfortable use. (Two of my tripods have no center column, one has a "rapid" column, and the studio tripod has a heavy duty geared column.)
Among the more affordable and well-made tripods, i'd suggest you take a look at Manfrotto. These aren't the lightest and Manfrotto heads with quick releases use a proprietary system, but are fairly widely sold, if you need another or replacement part. Or just get one without quick release for now and add a universal QR platform to it later.
I can tell you that Manfrotto are durable. I've got one that's about 30 years old (under the old Bogen brand name) and still working great. It's a big, heavy thing I don't like to haul around anymore, so I mostly only use it in studio. I have three Gitzo carbon fiber tripods I use in the field (all around 10 years old and still going strong).
In the past I've used used the Manfrotto similar to what they now sell as their "190" series. They now also offer a "290 series" which are similar, but with carbon fiber tubing instead of aluminum, for lighter weight and the other advantages CF offers.
Now, these may be larger than you feel you need for your camera. They might be more thany you want to spend, too. But they are sturdy and well made. Compare to smaller, lighter tripods offered by Manfrotto and others.
Both those Manfrotto are available as legsets only, where the head is purchased separately... or in kits with both legs and head. The kits can be a good deal, if they meet your particular needs well.
Hope this helps. Have fun shopping!
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
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