here are my few tips on this:
I have trouble with visualization and especially meditation.
1st. Start talking and thinking as if your visualisation and meditation are getting better and better. If it is not the case and you do not want to be lying, then think that it is improving every time you try it. (keep the positive outlook)
2nd. Do not concentrate on improving visualisation, that may or may not come later.
Instead of seeing it, you can know that it is there, wherever or whatever you want to try to visualise.
For example, close your eyes and think of an apple. You may see black screen, but you still know how an apple looks like.
Then think of how many colors an apple can have.
Try to recall the taste of an apple. Try to recall the scent of it.
Try to recall how an apple juice tastes. (all this with closed eyes)
This 'thinking' or 'recalling' how the apple (banana, orange or other things) is actually enough for your visualisation practices.
3rd. Easy things come easily. Be at ease when doing these exercises. Do them without any expectations, approach them as if you are curious if you will see something, and if you do not see anything - then it is ok too.
(p.s. i'm trying to avoid the usage of 'hard work' because hard work in this case (spiritual practices) is not the appropriate mindset.)
4th. Remember to keep the good cheer. If you have Harmfull thoughts, they may hinder your progress.
But if you have them,then it is ok. In that case only notice them (as if they are boring) and let them go.
5th. Start recalling dreams. Notice, whenever you recall a dream, you actually see what has happened there.