Paint tip

Tamiya paints - not the best...
I have tried many different types of paint - mainly acylics - for my models.  And my experience is mixed to say the least. 

Games Workshop are hit and miss - generally good but terrible pot design (the lid folds back so you have to keep moving it out of the way and they invariably spill the contents when you're opening them).

Coat d'Arms I like as I do Vallejo (the latter though does tend to have the odd problem where the pigment separates and requires vigorous shaking to get some consistency).

Humbrol acylics tend te be OK but the square pots are a disaster - I've had more spills opening them than any other.

I've also used some 'non-brands' from games shows which again are hit and miss.  Some have been good, some awful.

But Tamiya I've found to be a pain.  The shades tend to be right on the button for WW2 but they are woeful for mixing.  Even after a big shake you find big clumps of pigment at the bottom of the pot - and thin paint that needs 5 coats before covering anything.

So taking inspiration from my can of primer, I put a ball bearing in each Tamiya pot.  When you shake it, the bearing breaks up the clumps and the paint comes out much thicker.

It may work for the others (it may mean prizing the nozzle off the worst offenders in the Vallejo range).

But worth a try!