M2A2 construction tips?

The nice thing about Tamiya armor kits is that the drive sprocket and idler wheel are attached with friction using the poly caps. You can leave those parts off until you are ready to mount the tracks and then slide them all on at the same time (tracks, drive sprocket, idler wheel).

The easiest way to paint the road wheels is by painting them black and then using a circle template (available for a buck or so at a stationary store) and using the appropriate hole as the mask for the metal portion. Just put some masking tape over adjacent holes to prevent overspray.

Decals on modern US sand colored vehicles are fairly simple; just black markings. Add them before weathering. Sometimes the actual markings are spray painted on, other times they are stickers. You'll find both on the same vehicle. Stickers don't last as long as paint, so weather accordingly.

It does sound like your paint is a little thick. There shouldn't be any issues with the paint gluing down the hatches, but next time you may want to "work them" up and down with a toothpick as they dry so they don't get stuck open or closed.

I usually use a wash that won't effect the paint below. If I painted the tank in enamels, I'd wash with acrylics and vice versa. Although I often spray with a gloss coat before adding decals for better adhesion. Then hit it with a dull coat and start weathering from that point.

Paint color - If I remeber what I read, the Army/Marines color is on the darker side. I understand that that color was used in country. The color to use "factory fresh" is Sand - FS33531 by MM.

I'm from the mid 80's Bradley world so I may be a little off. My Bradley was painted "forest green"/Nato Green/Dark Green.... what ever LOL

When I built my Bradley M2A3 I used the Fruli Metal Tracks and I attached the upper/lower hull and just threaded the tracks around and then attached the final pin. On my other Bradley models I painted the upper/lower hull seperate and then fixed the tracks. After that I pressed the hulls together with to be held with the poly caps. After that I finished up the detail work.

See below....

M2A0 with the "rubber band" tracks

M3A0 with the "rubber band" tracks.

M2A0 with the Fruli Tracks

M2A3 with the Fruli Tracks

Hope that helped

You have already received some good advice, but here is some more...

1.) Paint: I used MM Acryl U.S. Army/Marines desert sand. It came out a little on the thick side (my fault) but also seems a bit on the dark side compared to photos I've seen. Should I be mixing it with white and about what ratio for a good scale effect?

The  U.S. Army/Marines Desert Sand color is not a US Federal Standard (FS) paint color.  It is based on a paint that was hastily bought in Saudi Arabia during the build-up to Operation Desert Storm (ODS, '90-'91) to quickly repaint NATO camo vehicles from Europe and the US as they came into theater.  As stated above, Testors Model Master Sand (FS 33531) is an almost perfect match for modern CARC Tan as seen on current vehicles.

2.) I found it hard to get the tracks in place even without the side armor attached. Would it be better to assemble the upper hull seperate from the lower and join them permanently post painting?

I don't generally have an issue with tracks, esp. those that go behind skirts.  The easiest way to attch them is to leave them apart until you are ready to attach them.  Feed one end of the tracks through the sprocket and around the road wheels, then attach the two ends of the track.  Once attached, simply rotate them so the connection point is hidden behind the skirts on the top of the road wheels.

3.) The hatches were glued in place but the hinge still works, however the paint glued them in place at the closed position. Should hatches be painted seperate and assembled later?  

You can do that, but usually, properly thinned paint will not "glue" them in place and they will still be movable after painting.

4.) I used an acrylic wash of red brown which stained the underlying paint and began to lift it off. Should there be a barrier coat between base and wash? Also what is the proper wash color and is oil/enamel better than acrylic for washes?  

Yes, if you are using acrylic paints, you have to seal the base coat before weathering washes and successive coats are added.  A dark brown is usally a good wash color for sand vehicles and an alomost black for darker vehicles.  I use enamels for the base coats and usually use acrylics for washes and weathering.  I also weather after applying decals and sealing them on, see no.5.

5.) Decals pre or post weathering?

I always add them before weathering so they weather the same as the rest of the vehicle.  Nothing looks worse to me than a nicely weathered vehicle with clean markings.  It just doesn't make sense to see them that way.

6.) what is the best way to paint the black tires? I heard a U.S. dime is the right size to lay over the tan portion then the wheels can be airbrushed. Does that work?

I use a circle template.  It is an artist's tool with  a bunch of pre-cut circles of different diameters cut into it. Paint the whole roadwheel flat black, then use the circle template to match the diameter of the metal wheel center and use it to mask off the rubber part and spray the center wheel color through it.  This is quick and easy.  Works great every time.

Good luck with the rest of it.