This is a summary of my longer Abathur Guide appropriate for players using Quick Match to get used to the hero.
Macro Goals
Playing Abathur in Quick Match is a great way to improve your macro skills. Everyone knows you are mostly enjoying the pajamas and little toy trains, but you can also learn macro.
Learn the maps, especially which bushes/smoke players use to hide.
Use the top panel to monitor ally health bars.
If you play Abathur well, opponents will be slowed, while your allies get shielding, experience, and healing.
Talents
Here is a set of generally useful talents appropriate for the chaos of Quick Match.
Start with Regenerative Microbes for healing. The spike burst talent would helps a dive team more, but at the start of a Quick Match game you cannot know if your team dives well. The locust talent would help more if the enemies lack waveclear, but in Quick Match players may not rotate lanes normally anyway.
At level 4 get Sustained Carapace. In Quick Match your team always needs more healing.
At level 7 get Vile Nests for slowing the opposing heroes. Your team can benefit from slowed opponents without careful teamwork.
At level 10 get Ultimate Evolution and have fun with it.
None of the level 13 or 20 talents are especially appropriate for Quick Match. Pick appropriately for structure damage, sniping, or healing.
At level 16 the normal choice is Envenomed Spikes, again because your team can benefit from slowed opponents without careful teamwork. However, if no ally is taking mercenary camps getting Locust Brood will allow you to claim camps by yourself. See my longer guide for details.
Abathur's Positioning
The locusts you emit only pressure lanes without opposing heroes. Use Deep Tunnel accordingly. Ask allies to destroy walls since this lowers opponents' vision of locusts.
In early game only body soak when opponents clump for objectives, by positioning yourself safely in farthest lane. In late game both teams clump for team fighting, so you can body soak more safely.
Also use Deep Tunnel to travel to unguarded objectives, including Pirate Coin Camps and dropped Spider Queen gems.
Symbiote
Minions should never die to your towers unsoaked: use Symbiote on those towers. Similarly, use Symbiote to soak minions fighting in the middle of a lane without heroes.
Make cooldowns efficient by using Symbiote+E+W+Q then leave Symbiote.
Toxic Nests
Place toxic nests to provide vision in bushes near the next team fight (objectives, boss, etc). Also place toxic nests on opponents' side of map in vertical paths along their rotation routes.
If you hover the mouse cursor over the toxic nest button, its range is faintly visible on the mini-map.
You can also place toxic nests in center of clumped enemy minions in lanes without heroes. (If the toxic nest deals the final damage to an enemy minion, your team soaks the experience. Try placing two, one at a time.)
If you have time, you can use place toxic nests to distract fort/keep shots away from allies.
Ultimate Evolution
Use Ultimate Evolution as team fights start, or the fight will end before Symbiote becomes available. Pick the ally for Ultimate Evolution based on position and mobility (often a global hero ally is best).
You can also use Ultimate Evolution to zone opponents away from objective without a full team fight.
