Which is first ? Tuning the parameters or selecting the model

Question

I've been reading about how we split our data into 3 parts; generally, we use the validation set to help us tune the parameters and the test set to have an unbiased estimate on how well does our model perform and thus we can compare models based on the result of the test set. However, i've also read that model selection shoud be done before tuning the parameters. I'm getting confused. Which one must be done before the other ? Is the validation set used for tuning ? If true, how are we supposed to do model selection before tuning the parameters ?