Congrats on becoming a REOnaut! Here are a few tips that I think would help. Not sure if you have any experience with dripping but, it's practically the same thing.
1. Prime atty first before you put it on your REO
*Drip 6 drops into your atty and let it rest for 10 minutes.
-With cartos, fill it up with the proper amount of juice. Then let it sit for 30 minutes.
2. You get about 5 hits or more depending on which atty you use. I'm primarily a 510 and 306 type of person so that's what I'm going to comment on. 510 can get to about 8 hits while 306's will be 5 or less. Biggest sign is a decrease in flavor. Also, if you taste a slight metallic flavor then your next hit will be VERY dry.
3. Blind Squonking is the easiest way for me and I think you will find it helpful as well.
*Lightly press the bottle while doing a dry hit (w/o pushing button)
*Once you hear a gurgle then immediately stop. (you can do a few dry hits to draw the juice into the atty but, this is optional)
*Simply start vaping.
Hope that helps. If you have anymore questions then don't hesitate to ask.