Deep-striking small 3-man suicide squads with Combi-weapons is a common strategy as Andrakis mentioned above. Combi-plasma's are very useful as well, they will be able to pop in and drop light vehicles or shred heavy infantry or HQ's. Don't expect these squads to stick around long though, hence suicide squads. Don't bother outfitting them with anything other than Combi-weapons. They are unlikely to live long enough to warrant any further upgrades.
The best equipment load-out is always dependent on what you plan to do with them but I'll throw a common build up...
5-Chaos Terminators mounted in a Land Raider with a Powerfist, Heavy Flamer and combi-weapons. I like using Combi-flamers or Combi-plasma myself as this squad is geared for ripping infantry up. As for Icons, I recommend Slaanesh for I4 armies so you can get killy before they have a chance to strike back, Khorne for super overkilly amount of attacks. Nurgle is good for keeping your Termies alive versus large numbers of low strength hits. While Tzeentch will keep you alive versus nasty power weapon wielding squads, HQ's and heavy weapons fire. These last two Icons are very spendy though and can make your Spendy Termy squad an even bigger point sink. Lastly Chaos Glory is cheap and will keep you from breaking after only taking a few casualties so the boys can keep stuck-in. Stuff em in the Raider and cruise up to your target, unload, shoot, assault.
I personally don't take heavy shooty Termie squads as there are better choices for your long range support. Like Obliterators, Havoks, Predators...
Just remember that Chaos Termies are cheap and flexible compared to Loyalist Termies and try and keep them cheap as possible, while still capable of fulfilling their intended function. Expect their deaths shortly after arrival and you shouldn't be to disappointed.
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