Question: do you use much wire for tubes, exhausts, etc? I want something to put on my 'Fexes, but I'm not sure what thickness to start with. I hear guitar string is good, but do music shops keep broken strings around that I could get from them? Are there other good sources I could mine?
On the IG side, pretty much all the vehicles are good. Try to keep the cost on your Russes under control, which generally means avoiding the Plasma sponsons. Give each vehicle/squad a dedicated role to fill and stick with it. Mixed Hellhound squads are bad, don't use them. Avoid squadrons of three vehicles, they almost always end up wasting firepower on a target. Valkyries are fantastic, don't be afraid to take them (unless you lack the $50/each for the model.) Mech IG in Chimeras is perfectly good these days, but have some unmounted squads as well to ferry around.
In the Inquisitorial side, the Mystics are your biggest gain; giving you free shots at demons, Marines, etc, is golden, especially in larger games where you're practically guaranteed to see some DSers. Getting easy access to Psychic Hood is also nice. A lot of the other stuff is mediocre and should probably be avoided, although something can be said for EL Inq + the poly Assassin (name escapes me, sorry). Inquisitors have access to some wacky and unique powers you might consider, and they can also have a shit ton of heavy bolters following them around. Medics + Acolytes allow you to make a squad a lot tougher, but you'll still roll in CC so be careful.