@derp
My thoughts.
Have you been working out long? Are you sensing that you're not quite doing the exercises as diagrams show? If so, get a trainer for a couple of sessions, and they will help improve your form and technique.
The benefit to signing on with a trainer is that they will help you keep motivated and on track towards your goals. For some people, this is worth the premium in price. Good trainers will remain in contact with you via text and e-mail to remind you of sessions and to pump you full of slogans to help you stay on target.
I've used them before. They were helpful. For average consumers, the best thing to do is go with your gym's trainers. Those trainers know the place well enough. If you like the training, then hire a private one.
Myself, I've been working out fairly regularly for about 20 years. I've done a lot of exercises and exercising, from when I was fit and in shape to the present. Frankly, I've gotten the most mileage out of online programs, but those have a plethora of routines available, along with the ability to track what you've been doing. I've said it a million times, but it's worth checking Daily Burn out.