Stem changing verbs
 

Hi, when dealing with stem changing verbs, is there a way of identifying them on sight or do I just have to memorise which ones are stem changers?

Thanks

Unfortunately, one mostly needs to memorize them.

Occasionally the infinitive ending (-ar, -er, -ir) plus the sounds in the last syllable of the verb can give you a clue about which stem changes will occur if the verb happens to be stem changing. But this isn't a reliable way to know whether or not the verb is stem-changing or not.

For example, verbs that change e->ie and o->ue (sentar, mostrar, jugar, querer, soler) are almost always -ar and -er verbs, while verbs that change e->ie/i or o->ue/u (sentir, dormir) and verbs that change e->i (pedir) are always -ir verbs.

Although some memorization can't be avoided, you don't have to memorize each and every verb.
Try using a conjugation manual. They group the kinds of verbs according to how they must be conjugated so you'll learn to identify which verbs are similar to the model, and conjugation will come natural to you over time.
Larousse has a manual called Conjugación Lengua Española, which I think can be found on Amazon.

Thanks guys, really helpful :)

I found that after about 10 years of speaking Spanish I was starting to develop an instinct for which unknown verbs would change, but it's a fallible instinct. There is a simple rule, but it's no use to you unless you already speak Latin fluently...

I speak latin as well I speak Klingon unfortunately.