I agree, taking a formation helps make Genestealers more "playable"
You'll Need a decent amount of terrain to do much of anything, but once you have the heart of your list (a Spawn of Cryptus, or a Broodlord Hunting Pack) You will want some Big Bugs.
Against
AM/
IG a Tyrannofex can be very good, Tyrannofex, Acid Spray, Thorax Hive : Electro Grubs (185, 200 if you add Adrenal) Can delete huge numbers of soldiers, and Haywire Vehicles. All that in a T6, W6, 2+ save package.

You'll also want some Synapse, so a Zoanthrope or two will help out, or use Warriors, with a Strangle Cannon (a Venom is OK as well) And I would use at least One Winged Tyrant for maximum Powah!
so something like...
HQ: Winged Tyrant, twin Brain Leeches, Thorax Hive : Electro grubs 240
Spawn of Cryptus...525??? or a Broodlord Hunting Pack 354?
Two Troops...Hormagaunts or Temagants, or Ripper Swarms 40 to 50 x2
Elite Zoey 50
Elite: Venomthrope 45
Thats around 700 points, then look at adding in some Big Bugs. I strongly reccomend Carnifexen, Tyrannofex, and Mawloc
A decent "Second HQ" would be a Tervigon, with a Thorax hive: Electro for a bout 205.
Good luck! And welcome to the Hive Mind!
Later you can add in a x30 Brood of Termigants, and change the Tervigon into a Troop, then add a second Winged Tyrant.