imperial guard tend to have the cheapest infantry avaliable to the imperium, so they are in high needs, but to rule out vehicles would be ignorant of there true power, the way to make them work, is three ways
Do you like to bombard the opponent with wave after wave of players, there weapons become usless because youve swarmed them? : Then is say a balance of
or do you like to rush into the opponent at lightning speed, jump out by suprise with a hail of gunfire, jump away again with the opponent cringing? : this is more of the balance, chimera's alongside guard regiments, you can move your 12", jump out, rapidfire there ass into the ground, jump back in next turn (you will lose troops, but at 6-7pts each?) and then continue to do that, with the points you could easily have 3-6 shock troops, and even fit a HS tank too, balance is 4:6
but, do you like to focus less on numbers, and beat the living daylights out of your opponents from a distance, plus have the type of weapons that will give nothing there armour save? : tanks, Basalisk and Leman Russ Demolisher, how you group them together is up to you, 2B with 1L, or the other way around, or maybe just 3 of a kind, basalisks, should in 6 turns be able to fire 6 times with the demolisher round, and the tank should never be attack (positioned correctly and as long as your not playing space wolf scouts) and with the leman russ, well, thats death on wheels, with its great front armour, you should just plough into the enemy, unloading the ultimate large blast template on them each turn, nothing gets a save and it will instant kill almost everything in exsistance, this plan should be infantry to tanks of 2:8
my personal view is option 3, there is nothing better than dropping a shell on a command squad and saying to the stunned opponent "thats 2's to kill....take your 9 armour saves, oh wait, you cant! muhahahaha"
but if you want ultimate numbers, you can fit 200 standard troops and a command squad for 1500 points, lets face it that wont be easy to get rid of, unless you play hoard tyranids in which case you are royally screwed!