Yorulunca otururum. Yeniden başlarım, kafam karışınca.

My attempt, and a breakdown to hopefully help

yorulmak = to get tired

yorulunca = when tired

oturmak = to sit

otururum = I sit, i will sit

yeniden başlamak = to start again

kafam = my head (my mind/my brain)

karışmak = to mix

kafam karışınca = when I´m confused

So the message is

When I´m tired I´ll sit down. I´ll start again when I´m confused.

İ sit when im tired. i star again, when my head confuse.

my try

I sit down/ take a rest when Im tired. I make a new start when Im confused

ahmet_a1b2´s translation is the most correct. Aorist tense (-irim -ırım) is a tricky one, but a good rule of thumb is that it´s mostly used when we talk about our habits or things we do daily, like "Her sabah güzelce kahvaltı yaparım." (Each morning I have a decent breakfast.)

Hope it was helpful,

-Jansay