Position the patient: i like knees slightly bent, patient slightly rolled on the side of the bed towards me, head up = all this increases intraabdominal pressure a bit which will make drainage faster. Guard rail down. Bed very very high to make the job as easy on my back as possible.
POCUS if you can to visualize a fat pocket in the RLQ or LLQ.
For therapuetic: If your catheter is not fenestrated, then once youre sterilized, grab an 18G blunt tip and stab some holes along the catheter - that way you don't have to worry about some intestine or tissue blocking the very tip of the catheter.
Saftey needle/Turkel makes the actual procedure pretty easy.
If the abdomen is not like disgustingly tense then I find the risk of leak is pretty low so I'll try and avoid Z-lining or going on an angle. Otherwise I get a med student or nurse to lightly stretch the skin when I'm going in so I can have two hands on the needle.
Once you're all connected, put the bottle on the ground to maximize gravity drainage.
If the flow stops, you'll have to trouble shoot but most likely something is stuck to your catheter on the inside of the abdomen - try sterily adjusting the catheter, twist it a bit, or pull it out a bit. Or ask the patient to adjust his belly.