LambdaFF, that silver paint should work really good, better than copper paint. Just make sure you have a good consistent coat. The reason I like to use the spray paint base coat is because in the case where there might be a hole/crack/break ect. in my copper paint the base layer will still provide conductivity. It's not necessary just something extra I do. I do recommend applying two coats though, again just to make sure the entire surface is conductive.

Also make sure when you plate the part that there are multiple contact paints with whatever wire you are using to hang the part. If you're familiar with a voltage divider you can think about the surface of your part as being a giant voltage divider. So the further a point on the surface is from the wire bringing in the electrical charge the more resistance in the paint it will encounter. For example say a point is 5mm from your wire contact, and another is 10mm away. Assuming consistent surface resistance. The point further away will experience half the current the closer point experiences, this assumes away several other factors but as a rule of thumb the further a point is from the source of current on your part the slower the plating at that point. The resulting effect is that the plating will slowly migrate across the surface of the part until the whole surface has an initial layer of metal and then the plating speed will be basically the same across the part.

If you bought a kit you probably don't have to worry about temperature. Temperature increases allow for faster plating speeds. Here is a great discussion on bath temperature. http://www.finishing.com/1600-1799/1721.shtml

There is a plethora of information at finishing.com and I've learned a ton at that site. But yeah, if you bought a kit I'd follow the instructions for the kit.

I hope that helps. I'm by no means an expert. I'm a mechanical engineer by trade and picked up electroplating with the purpose of plating 3D prints for functional use.