Remember what the guided meditations had you do, and then do it. I actually found it easier to meditate without the guide because their voice wasn't always startling me out of my zone. I usually end up just making myself comfortable and focusing on my breathing for however long I like.
I haven’t developed that much but I will start by memorising a simple meditation that I’m familiar with and practice till I'm comfortable.
You can just do one for either five or ten minutes without guidance in a chair or laying down while you take a deep breath at the beginning of your meditation
You just have to keep practicing everyday. Noticing changes in you’re life from your mood to your physical well-being is a good indicator that you’re ready to move on to unguided mediations. You need to practice everyday and have patience. Mindfulness takes time.
Start low (5 minutes at a time). Try and focus on just your breath—you can use a small phrase like “in, out” if it helps to focus your attention. I usually try to pick a spot of my body to focus on (either chest rising, stomach, nose). If you’re really having trouble focusing you can also try a walking meditation—just walk and focus on your steps and your surroundings!
Just keep it simple; focus on your breath, relaxing your body and if your mind wanders it's ok. When you notice just bring it back to your breathing. Counting your inhales helps me to focus. It helps to set a timer too.