If you can't do chin ups and/or dips with your body weight or can't do very many, you need to get yourself some resistance bands. Even if you don't need resistance bands for chin ups and dips, you should still get resistance bands. They come in very useful.
You can use different resistances to help you more in the beginning and decrease that resistance as you make strength gains.
You can use the bands for higher rep ranges along with certain workout programs within this manual.
For example, many people can't do 15 body weight pull ups but they can do 8 to 10. You can use a resistance band to help you get 15 reps and simply get rid of that resistance band when you get to the lower rep ranges.
Eventually, you won't need the resistance bands as you get stronger BUT you will be able to use them for other exercises.
I do not recommend the assisted machines. Instead, I recommend resistance bands. They work much, much better and will help you get stronger on chin ups and dips at a much faster rate.
An example of another use for resistance bands… you can use them for push ups to easily add resistance to one of the best chest exercises. Push ups are a great exercise but it was difficult to add resistance safely until resistance bands were invented.
That's just one of their many uses. Trust me on this one. Resistance bands are well worth the money. They are a great addition to your weight lifting equipment arsenal.