I looking for some help in making my Void Master more effective in combat. Can I get some weapon/talent advice so I don't just feel like my character is completely ineffectual in a fight?

Anyone?

Walk softly... and carry a big gun.

In this system, combat effectiveness is more a matter of tactics then a particular set of combat skills. Generally your lower cost skills will involve vehicle operation so things like sentinels and tanks are your forte on the ground. In the Air your party will have to rely on you to keep them alive since that's where they will be mostly helpless.

As for gear, consider my personal favorite for a basic weapon: The Storm bolter!

Are you starting a new PC or looking at improving an already playing PC.

Either way a little bit about his current setup will help

Spend XP to acquire skill in heavy weapons systems. Point heavy weapons on gun cutter you usually fly around in at opponents. Squeeze the trigger. Have your Ad Mech buddy rig the gun cutter to drop bombs. Carry napalm (a.k.a. promethium). Want them alive? Carry big net. In a tank? Mount lascannon. Got more PF? Acquire conversion beam. Need area of effect? Cluster munitions. Missiles are your friend. Acquire man-portable systems for those situations when the gun cutter can't go there.

Think big.

Think bigger.

Careers do not have a lot of options, and it'll take you awhile to get through the ranks. Rank 1 is almost always spent on characteristic advances, and it isn't until Rank 2 that you start to get a LITTLE bit of customization.

I suggest that you look at taking an Alternative Career for Rank 1/2 if possible, and those can be tailored based off of your character request. Otherwise as indicated, decide what sort of role you want to fill in combat or social situation, and bling yourself out for such a goal.

Jump pack. My first character was a Void Master, and he turned into a beast. He can make a Raptor or an Assault Marine nod their head in approval.

Regardless of if you are shooty or stabby, as a VM, you have the skills and talents (eventually) to use a jump pack.

Also, Pressure Carapace is a useful armour, regardless of career, so get some of that. If I can think of more, I'll post later.