I have an old bridge camera Lumix FZ20
Oh, easy, thought we were talking SLR
You have more depth of field at 2.8 with your Panasonic than you would with a SLR.
I'm not familiar with Panasonic But I'm sure I can figure it out
There should be a Macro mode. It'll say Macro or there will be a flower symbol. You may be able to engage Macro in conjunction with another program like shutter priority. Like I said I'm not familiar with Panasonic but I'm sure there will be a Macro mode there somewhere.
This mode may automatically choose the aperture for you. And if it does it will most likely choose f8. F8 on your camera will give you more depth of field than you'd have with a SLR at f22
If Macro mode lets you choose the aperture, for this test choose 2.8 because this will allow for a faster shutter speed. The faster the shutter speed the less chance of blur due to camera shake or blur from your subject moving.
Set your ISO to the lowest number your camera has, should be around 100. Do not use automatic ISO if that's an option. Low ISO gives you a prettier picture, less noise.
Turn off your flash, the inboard flash can be used but that takes more settings to play around with. Way too easy to blow out the highlights with flash when shooting Macro.
Now, for macro photography "No camera movement" is very important. A tripod or a stationary object to hold your camera is a must. It doesn't matter what you want to photograph just pick something tiny.
You want some decent lighting and you can position your camera on a table a few inches away from your subject.
Look closely when your camera focuses. You can't get too close but you want to be close enough to focus properly. You want to make sure you're using spot focus, where your focus point is in the center of your lens. For Macro you're only using the center of your lens
Let me know how this works out.