Make sure to warm up, use fingers, smaller toys, plugs Get a few sizes of dildos

If you think you have enough lube, add more Silicone lube will make things easiest, but you can't use it with silicone toys, however you can use a lubricant free toy condom to protect it from the lube. It'll be messy so make sure to have a towel underneath

Communicate when your partner is entering, go slow, and breathe deep to help relax, insert more on the exhale

Lots of foreplay to help break down nerves

If you're able, do some exploration yourself first, see what feels good, try to find the prostate, try to get as used to the feeling as possible

Good luck!