Welcome to the darkside ..... we knew you couldn't resist forever !!!!! (insert evil laugh)
For a first armour build, I would suggest a kit from Tamiya. They may be a little more expensive, but the engineering of these kits makes them a joy to work on. Any of their newer kits are simply superb such as the Tigers, King Tigers, Panthers, or Shermans. Their Russian T-34's are a little older but still build up nicely. As far as figure kits go, i would suggest you look at Dragon's line of figures. They are crisper in their detail and have a far wider selection.
As far as general rules of thumb for building armour, you will get many different answers to this.
Here is how I do mine, and I only refer to tanks here. Artillery and softskins would be entirely different.
I assemble as much of the kit as possible before doing any painting except for the tracks. This includes all tools, etc. I then paint each assembly, the turret, the hull, the tracks with their base colours. Camo (if needed) is than painted. I then paint any details that are a different from the base colour such as wooden tool handles, shovel blades, etc. I then apply a gloss coat to apply the decals followed by a dullcoat to bring the vehicle back to a matt finish. Any added stowage would now be placed on the vehicle. Now I would weather the vehicle using washes & drybrushing. Add the weathered tracks to the vehicle and finish it up with pastel chalks to give a dusty appearance.
These are the basic steps that I use and i hope this helps a bit.
Happy Modelling and God Bless
Robert