If you have just a bit more of smoke than usual do a code scanning to check if mixture is rich or lean or if there is misfire or other problem that can affect the engine.
Dark thick smoke is symptom of unburned fuel or oil getting into the cylinder. The smoke can be the result of rich mixture, piston ring problems, valve problems, ring problems or misfire. EGR and PCV system problems also result in smoke from exhaust.
If smoke is only at start and it is dark gray it is probably because of incorrect mixture resulting from another problem.
If problem is piston rings or valves the smoke will be black, thick and smelly because oil gets burned in cylinders. The smoke in this case is not only at start.
- Check if you have spark in all cylinders.
- Check if one or more of the spark plugs is dirtier than the others. That will tell you if problem is with that (or those) cylinders only.
- Do a DTC code scanning using an OBDII reader. In US the code can be done for free at Autozone.
Thick white smoke is instead symptom of water (or coolant) getting into the cylinder. Check if the coolant fluid level is going down by itself. Look for traces of fuel in coolant reservoir. Do a compression test to find out if there is head gasket leakage inside the engine.