Frames fit loose.. Any ideas?

Im trying to build as many things around the house as possible. I like doing it but one issue. I can't get pocket joints to be secure nice and tight. I bought a cheap Kreg jig tool and can't seem to get the hang of it. My pre holes are in the right location, my screws are the right size, they're just not tight! So on my last project (using overlapping frames) I just screwed the dang things together and that held them together. I'm making another flag frame for my dad and want it to be better than the one I did before. How can I get these joints to be TIGHT? Any other ideas y'all have? I'd like to master this part of carpentry.



Here are some pics for reference, you'll notice my joints are sloppy and loose looking.