One thing I have found useful is the use of EMERY BOARDS ...

they make great little sanding tools for tight areas and broad sanding .... I prefer revlon... they have a thin hardened backing and two different grits fine and course
I'm sure many of you know of this tool.... but some may not....
I think they are a little more versatile than modelling files... as the files teeth don't go all the way to the end
The emery boards can be trimmed with some durable shears.to any shape needed... so can go deep into triangulated areas .. usually not accessible to files
and for the beginner .. a cheap alternative to buying a set of files
HAVE FUN MODELLING

ALPHA