To compile a standalone with root libraries:
g++ -Wall $(root-config --cflags) -c "%f"

To compile and link (generate) a standalone with root libraries:
g++ -Wextra -Og -g -Wall $(root-config --cflags --glibs) -o "%e" "%f"

To add RooFit to the mix, add:
-L $ROOTSYS/lib -lRooFitCore -lRooFit

My ROOT distribution was configured using:
./configure linuxx8664gcc --prefix=/usr/local --all --enable-gsl-shared

To run pyROOT (import ROOT hangs otherwise):
export PYTHONPATH="/usr/local/lib/root/"