You can check out this thread
Free Classic Beginner's PE Routine! for PE exercises for beginners. These exercises will improve your stamina, erection quality and increase size of your penis by just using your own hands. It's safe (if done properly) and free.
As for the extenders, well you have to spend money on that and from what I read on PE forums a lot of people say manual exercises are better than the extenders and the ones that use extenders they still do some type of manual exercises. So it's all up to you, if you have the extra cash to spend on extenders, then go for it. Good luck.:smile: