Short version: I would put the BIB files to
~/texmf/bibtex/bib/myfiles/myfile.bib and style files to
~/texmf/tex/latex/myfiles/myfile.sty for example.
Long version: try
which will show you where you can put your local files, so that TeX will find them out-of-the-box. By default this is
~/texmf (for your personal files) and
/usr/local/texlive/texmf-local (for system-wide additions). Inside that tree you need to follow TDS standard. For BIB files that would be:
BIBINPUTS = .;$TEXMF/bibtex/bib//
That is default value in TeX Live 2011 at least. You may check
texmf.cnf on your system if the value is any different, or try to run one of the following commands:
kpsewhich --expand-path '$BIBINPUTS'
This will tell you where BibTeX searches for BIB files.
If you need those files only for a couple of projects and/or don't want to pollute your home folder, the cheapest trick is to create a TDS structure anywhere on the disk and only set
TEXMFHOME to point to that location.
BIBINPUTS is not recommended. Setting
PATH only helps you to find binaries like
pdftex, but then
pdftex should be able to find
texmf.cnf and that file contains enough information to find everything else. You can override any setting from
texmf.cnf with environmental variables, but I would suggest you to place the files to locations where TeX expects them as opposed to setting variables.