Mixing In A Crew-Neck Tee With A Blazer And Chinos - Where To Start?

Gents, I need a little guidance with an outfit.

The last few weeks I've been out, I've kept it to a blazer, shirt, chino combo - which (for me) is as dressy as I want to go during the summer. I have plans this sunday, but I want to reign it in just a little, and mix a t-shirt instead of a shirt. I just don't know where to start.

My options for mixing are:

blazers - blue (almost like a "light" navy), burgundy, and grey
Chinos - royal blue (kinda pastel shaded), navy, grey

I'll almost certainly where my light-tan brogues.

I have no idea what colour t-shirt to mix in, and my limited knowledge of look-books has not made it any clearer.

I'd definitely prefer a crew neck, and as I've spent so much on clothes recently, I don't want to spend too much. A maximum of £25 really.

Any ideas of colour combos? stripes?

PS - for what its worth, I'm 30 - 6'3, so something suitable for my age also

A subtle stripe maybe? H and M do some cheap crews with very subtly striped designs. Mixing full on breton stripes with a blazer, esp navy, can look rather "sailory" sometimes.

Plain white, grey or black tees are the best option here.

I like the sound of burgundy blazer, grey t-shirt, grey chinos and tan shoes

Match the grey of the tee and chinos closely so that the blazer and shoes really pop

Man, I love this forum.

Lads, salute.