Get to know the composition of your party and be sure to take their strengths and weaknesses into consideration.
A strong combat oriented mage, or a powerfull spirit summoner, both of which you can build straight out of the box (which doesn't mean they can't get even better with experience, but you can be pretty good at either when you first start) will REALLY mess up mundane opponents unless they have magical support of their own. Conversely, if the party lacks strong magical support be careful how much magic you throw at them, as magic can rapidly lay out an unsupported mundane character. Its a common axiom to geek the mage first, then the troll next. If the mage is a troll, well, hope you brought clean underwear chummer, the alpha strike has your name on it.
Give your players some guidance when it comes to building their characters. The build point system is very flexible, with very little forced game balance. You can build characters of very disparate power levels on the same build points depending on how much you optimize and how many of the tricks you learn. Do not be afraid to tell players that they need to tone down a character, or that they need to optimize a character, to get people in more or less the same range of effectiveness. If your "weapon's expert" only is rolling 10 dice after the smartlink, and your investigator has 15 with his pistol, something is wrong. Neither character is wrong in and of itself, there are tables where both will fit in fine, but when people are better with their secondary jobs than the specialist are with their specialty, then something has gone wrong with the build. It is also very hard to write combat encounters for groups where one guy has 22 dice to hit and 17 to dodge, and the next guy is literally half that level. Again, neither character is wrong or right in the abstract, it depends on the campaign and the GMs take on things, but its a bugger to have them at the same table.
Having said that, some characters will be less fit for combat than others. Technomancers in particular really suck in meat space right out of creation. They can do some incredible things with technology, things that the hackers cant touch, but they are kind of like a early edition DnD wizard. Unless they happen to have a combat drone wrapped around them, which isn't always possible, they can be taken out by a cranky boy scout with a 2x4. While there should be times you pull people out of their comfort zones, remember this is a fairly lethal game. At least some of the time the non-combatants need to be able to work from the van, ride in the drone, or otherwise contribute without having their spleen handed to them.
Collectively, the group should have combat, matrix, and magic covered. If they do they have the makings of a good team. If they can't cover one of those to at least some degree it might be time to re-balance the party.
Apart from that, there are many specialties. Some teams are good at infiltration and B/E. Some are more paramilitary, lots of gun bunnies and demolitions guys. Others are more focused on investigation, surveillance, and detective work. A good fixer knows what a team will excel at, and connects clients with teams that fit the needs of a mission. Thats a polite way of saying to write stories that play to the team's strength, and that pull them out of their comfort zone in interesting and entertaining ways, not ways that are hard stops for the story or that will just get them killed.