to reply you on handbrushing.
Acrylics paints are excellent for this
Brands like Tamiya, Mr Hobby Aqueous, Vallejo, AK interactive.
All can be thinned down with either water or acrylic thinner.
Brushes also plays a part in hand painting.
There are synthetic brushes, natural hair brushes and hybrids.
Art friends do sells them, you can get cheap sable brushes there.
There are many videos on youtube that can help you.
As this is an extensive subject, you can do a search for Warhammer miniature hobby painting on youtube or google.
The techniques used are similar.
Hope this helps.
As for the guy with panel line issues, care to explain the type of panel line material used?
Micro pen? Tamiya panel accent?
for basics, micro pen can go all over anything and can be cleaned up with a hard rubber/eraser.
For tamiya panel accent, it is enamel based.
It is better for you to gloss the surface so the liquid flows better. It can be cleaned up using enamel thinner, zippo liquid or Isopropyl alcohol.
Then decal up and finish up with the top coat of your desire.