Its hard to give good advice without knowing the specifics of the GM's style. Hacking in particular can be either really cool or totally useless depending on how the GM integrates it into the game. Many GMs prefer not to deal with it at all. If you are thinking of a hacker type character be sure to talk it over the GM first.
Another issue is what sourcebooks are in play for the game. As with most RPGs the expansion sourcebooks have some of the more potent stuff.
If you want a combat heavy build you have numerous options. Your first choice is magic, or not magic. An Adept is a Magic based character that uses his magic to increase his physical abilities. Its good for making a character that specializes in one thing, but he'll be limited in other areas. A mundane character can do some of the same things with Cyberware or Bioware as an Adept can, but tends to be really good at a lot of things rather than the best at one narrow focus like an Adept. If you are going to be playing for a while, an Adept that gives up a little magic to take some Cyberware or Bioware is usually the most potent choice. You can spend mos of your starting resources for Bioware, and a little for magic, then once the game starts use most of your karma to boost your magical abilities.
You also have to decide, Bioware or Cyberware. Cyberware is cheap and gives you the most bang for your buck, but its much less essence friendly than Bioware and much easier to detect. Essence is the mechanic that determines how much modification you can handle, and also directly subtracts from your Magic attribute, so if you decide to go the Adept route, Bioware is a better choice. If subtlety doesn't matter, and you are playing a mundane character, and the game won't be going on for a long time Cyberware is a much better choice because of the cheaper up front cost.
In general, you are best off starting out with high Attributes and low skills, and advancing skills in game, its a lot cheaper. Keep in mind that during the character creation process it costs 10 points to increase an attribute by one up to a maximum of 5, and 25 points to go to 6. Once you start the game it costs New Attribute value X5 (or X3 if you aren't using the errata), so you are much better off min-maxing your attributes at character creation, and increase the low ones once the game begins. The same thing for skills.
Specializations are also much cheaper in game that at character creation. If you are going to be playing a while, specialize once you start.
The single biggest thing to maximize for combat is maximizing your number of initiative passes. You can do it with magic, or with Cyberware or Bioware, but you won't last long if you are acting once for every three times as everyone else.
As for physical attributes, Agility is good for combat offense, Reaction is important for not getting hit. Body is important for surviving getting hit. Strength is a somewhat of a dump stat. Shadowrun is a very lethal game, and in general you are better off trying to avoid getting hit than trying to soak damage.
Two very important skills are Dodge (not getting hit) and Perception, (seeing what's coming).
Thats all I have time for right now, I have to go back to work. The best resource for Shadowrun is the Dumpshock forums, you can get a lot more advice on the game than you'll get here.