The best way to grow your confidence in sampling is to take your favourite sample and becoming a master at manipulating it.
Chop it, splice it reorder it, layer it at half speed or double speed. Change the bpm and do the exercises again.
Do 4 bar 8 bar 16 bar edits with the sample. Play with the quantize in your edits. Turn the quantize off.
Understand every element of the sample your using, learn how to manipulate it beyond recognition, add effects, learn eq techniques.
Train your eyes to get used to where each instrument sits in the bar so that it becomes second nature.
Once you master the sample, add more instruments, Add some bass, some stabs, pads and leads or what ever you choose to add and you will find you will be able to visualize where each instrument can sit on your composition.
Dedicate a good month or so becoming a master of your favourite sample.
Hopefully it isn't just a boom bap sample. Use a real break to hone your skills, amen, funky drummer or something along those lines.
You want all the elements of a drum kit to play with.
This exercise will give you really good confidence in moving forward as a producer, repetition is the key here.
Don't chop and Change for the sake of it. If it's a sample you love it won't get boring.
You might get fatigued or run out of ideas, just chill and find other producers who use the same sample as you and listen to it from an analytical approach.
Then take what you learned and put it into practice.
Even if it means recreating the track. Your confidence and understanding will grow quickly if your in this for the long haul and you really want it.