why not try what im doing(check my protein synthesis post).Its pretty safe and u can use a piece of plank and put it on ur bed or chair as a incline bench.

Btw if u cant do a pullup u can just jump and just lower yourself slowly and repeat that for 10 reps for 3 sets and then after 6-7 workouts you will be able to do your first pullup!

And use a timer, check one from the internet

1:30 min rest and then 30 seconds workout.That way you wont be slacking off and do my 20 sets in exactly 40 mins.

in 1.5-2 years if u keep it up without any breaks you should look very nice.HIGH FIVE!