hey Lolita!
I myself am still working on my relationship with God and Christ. Ive heard of many ways of deepening it but a big one of course is reading his word as much or as often as you can. Joshua 1:9: Keep this Book of the Law always on your lips; meditate on it day and night, so that you may be careful to do everything written in it. Then you will be prosperous and successful.
I also find praying and talking to God at a specific time but also just whenever is a good thing. Discuss decisions with him when they come, talk to him about about how you feel when something happens. 1 Peter 5:7: Cast all your anxiety on him because he cares for you.
If you also have anyone else who is a Christian around you, you could try talking to them and asking how they stay close or maintain their relationship with God. Finding a weekly prayer group, youth group or church community (in person or online) can help.
Hope this helped, and if you have any more questions or so please ask!
Have a blessed day <3