I personally feel at one with water, especially the bluest sea, here where I live the water is brown and I don't seem to connect to it, it needs to be blue for me, I don't like to be in it, just to watch the waves , hear the waves and when I close my eyes near the water I feel totally relaxed and I can get into a very meditive state just by day dreaming at it.
Trees , flowers, grass
just lay down near some beautiful flowers and watch them, smell them, watch bees and insects on them, just daydream at them and you may find you are deeply relaxed.
I tried gazing at a tree the other day and found myself needing to touch it, when I touched it I closed my eyes and felt connected to the tree, even thought I felt it vibrating but that could have just been my imagination lol.
some people find that holding crystals in their hand whilst trying to meditate can help them to relax, I like to have a few different crystals in my hand that I rotate as I am trying to relax.
use your third eye
sometimes when I find it hard to visualise when meditating I use my third eye, I just focus on the are between my eyes on my forehead, and find it easier to try to think of a colour to appear there, blue or purple works for me, maybe if you try it you may find it easier to go from that to visualising what you want to see.
use music, or nature sounds.
most sites will tell you that you need complete silence to meditate but I don't think that is the case, for example my autistic daughter has to listen to music full blast with her headphones at school as this helps her concentrate.
so maybe in some people certain sounds may help, its all about experimenting and finding what works for you.
this is what is really working foe me at the moment and my visualisation has been improving as well.
im not good at visualising but I am good at writing, so once I close my eyes rather than trying to see myself in a garden or by the sea, I start to tell myself a story of what I want to see, so if I want to be at the beach.
ill start by describing myself leaving the house, ill describe the weather, and then just describe what I see as I am walking or travelling to the beach and what has been happening is because I am writing the story as I go along and im so relaxed I have been finding myself literally dreaming of what im describing whilst im still awake.