The good thing about 5x5 is that you start with minimal weights - like an empty bar - and spend your first couple of weeks training with "easy" weight. This time is really for you to learn the movements. There's a wealth of information out there on how to do these movements properly. Injury is always a possibility, but if you start light and progress steadily, the risk of it is substantially diminished.

A coach is a great resource, but a) most trainers in gyms are not strength coaches, and range from actively harmful to wonderful, and there's not really any way for the novice to know which they are, and b) legit strength coaches are expensive. I'd recommend self-study and starting lightly before a coach, personally, but if having a coach is the difference between you lifting and not lifting, get the coach.

Alan Thrall has 3 really good beginner videos on the S/B/D movements:

* https://www.youtube.com/watch?v=bs_Ej32IYgo

* https://www.youtube.com/watch?v=wYREQkVtvEc

* https://www.youtube.com/watch?v=BYKScL2sgCs

Also check out the JTS pillars series. JTS are legends in powerlifting, and these videos can really help tune up technique.

* https://www.jtsstrength.com/pillars-squat-technique/?v=7516f...

* https://www.jtsstrength.com/pillars-bench-technique/?v=7516f...

* https://www.jtsstrength.com/pillars-deadlift-technique/?v=75...

There's also https://www.reddit.com/r/formcheck (and r/fitness and r/stronglifts5x5) which can be valuable resources for getting help fixing particular problems.