Well Jack I think your figures and tanks are pretty good for a brush and some enamels. Not sure about the red-coats and the Challenger though- fairly sure thats not historically accurate

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You say you are in monetary crisis- that sucks- do you have any funds to spend? There is some cheap equipment out there that could lead to a marked improvment in your finishes without too much cost.
If you haven't got the funds to spare then some pointers (apologies if some if this seems condescening- I'm not sure of your skill/experience so I'm just writing some basic, relevant things) :
1. Thin your paints nicely before applying them- if this is done sufficiently then the visible brushstrokes in the paint is lessened. Be sure to mix them up thoroughly aswell before using them.
2. Make sure the thinner your using isn't too dirty- if you have it in a pot to clean the brushes change it out before it gets too dirty.
3. Don't mash your brushes off the bottom of a cup etc when you wash them of paint- rapidly swirl them about- this keeps the brush better for longer.
4. You can achieve a few different weathering techniques with enamels, however remember that since your base paints are enamel you will need to varnish your model to protect this layer of paint before you beging any of these techniques with enamel paints:
Filter- very heavily thinned paint (try a brown or earthy color) paint applied in stages all over the model. This should subtly alter the color of the vehicle and bring camo schemes together nicely. Try 5 parts thinner to 1 part paint.
Wash- This is thinned about 2 parts thinner to one part paint. Try darker colors like black or dark brown. You can apply this around seam lines and detail (like rivets etc) for a pin-wash which accentuates the detail or a general wash which is applied all over the model to give a dirty, well used look.
Drybrushing- This will represent general wear and tear on the vehicle. If you have a green color on your vehicle then your drybrushing color should be a lighter shade. Put paint on the brush but take nearly all of it off on a piece of cloth/kitchen paper and then run the brush over areas of detail.
Chipping- To represent areas where the paint has flaked or scraped off then you use small dabs of color in random pattersn around areas of likely high-use- like a hatch opening. Best colors for this are dark greys and dark browns for rust. To add another dimension you can also use a lighter color of your base to add a large chip and then, to represent deep scratches/chips, use a dark brown color inside the lighter color.
If it was me I would do these things in this order:
Drybrushing
Chipping
Filter
Wash
Well I hope this helps a bit Jack. Welcome to the site and keep us posted on your projects!