Opps. Seems like I deleted the text so here it goes again.
I have a Tamiya Halftrack and it comes in dark olive green. However I want to achieve that weathered look of light greenish yellowish color. How do I do that?

And the kit comes with bags,canvas and jerry cans. How do I paint it to look realistic like the ones in the gallery?

You have to mix your own color. You should paint on a base coat of straight up OD or primer of some sort (of your choosing). Then mix your own color of OD + a bit of dark yellow or buff to get the achieved faded look. Then apply that over the OD base. You have a couple of options, if you want an all over look just paint it all. If you want a faded edge look stick to the edges of each panels/area and work you paint fading it to the middle.
I kinda left this basic - I don't know if you have an airbrush or not. If you have an air brush the fade is much easier to achieve. Mix your color and set your psi a bit low around 15. Then work a med/fine tip around the edges of the base coated 1/2 track.

This is a start - to get you thinking about the process - ask more questions.

The gear - to get that realistic I replaced the straps with foil ones or scale rope (thread). I carved away the pre-molded ones and added mine. I painted them a variety of shades of OD. A couple I made kakhi. If you want to go an extra step. You can cover it with tissue paper to give it a nice texture.

I guess - I would recommend you kinda work out what you want and the detail at which you want to go and ask a few more questions.
If it's the M3A2 with the 8 figs. I just go done with that in December and can fill you in more as you go.

Well I have a Badger airbrush. Do I need to prime my kit in a grey primer and then spray on the yellow + olive drab coat as my base paint?
Btw slodder, can I see pics of your model?

I don't prime with gray then paint OD. I simply go right to OD. I know others prime first. I think it has a lot to do with if you have PE and resin added to the kit. If you're doing OOTB build stright OD should be fine. That's what I did. I'd go a layer of base OD, then mix the yellowish.

As far as the AB - I'd use the fine needle and know that two passes may be necessary to get the width you want. That because I'm a big fan of multiple passes with AB's sandpaper, knives etc. Slow and steady is my pace.

I'll take some photos this weekend and send them to you.

I would mix a little yellow into the green when painting. Don't know if it will work, but its worth a try.

G-Luck!

~Chip

Well can anyone answer my 2nd question into how to paint realistic looking bags, canvas and jerry cans?

For the second one, I paint them in a different shade green from the vehichle or kaki(usually acrylic), I wash with burnt sienna (oil + zippo lighter fuel), and drybrush with naples yellow (oil).
Ciao