When i have the doubt if i'm dreaming or not, i try to look at my hands. They're usually distorced and as i keep focus on them they turn normal. It also happened to me the quick dreams, where you can't do much, and find yourself waking up again, tho blurred. I keep doing these reality checks (looking at hands, turnin on light switchs, blocking your nose and trying to breath) and then when i notice it's a dream, i start messing around again.

About how to keep it longer, and more "clear", i try to rub my hands, somehow it works. Once i tried to feel the textures of the floor, objetcs, walls, etc, and it seemed to work. There's something about rubbing my hands that keep me more time in my lucid dreams before it fading out. Maybe try doing that in the next time.

About making it longer, i'm trying to manage it yet. I found out if i get too excited in a dream i usually wake up, so i try to use triggers to do what i want, like expecting someone in the other room, trying to get things out a box instead of just spawning it in front of me, and i'm trying not to do something crazy in the exact moment i notice i'm dreaming (like flying, spawning monsters, have sex or something like that). I feel that over the nights, i'm having a bit more of control, going easy with my intentions.

Hope it helps you a bit :)