Unless you are going with a
HQ/Elites/
FA/Heavy army with minimal troops (so your points go to non-troops selections) you pretty much never want to run Grenadiers.
Not good for a new player anyway.
DH Termies should have psycannons.
IG infantry platoons should have las or autocannons.
The
LR should have 3xhb.
Don't play bassies.
You can run alot of
LC specialists and elite vets, toss in a few hellhounds (or apparently sentinel squadrons with heavy flamers) and you have a very nasty list.
However,
LC are expensive.
DH Termies are very expensive.
What kind of army do you want to run?
IG are about the only army where mixing mech and non-mech works out allright.
They are a excellent gunline army.
Flamers + lascannons don't mix.
And those are my random thoughts.