Boyfriend is really girthy, and I am less than accommodating - would like some advice/recommendations!

I'll try to keep this concise, but here it goes!

My boyfriend and I just recently started having sex, and both of us aren't super sexually experienced. He has a lot of girth, and I'm pretty tight, so it's kind of painful when we try to have intercourse.

I know that Kegel exercises can help, working up to it with toys and/or fingers, lots of lube, a lot of arousal, and lots of practice (which I'm looking forward to).

I'm just curious if there are specific types of lube (I've heard that water-based is better, but any specific type or brand?), or loosening-type things that might make it even easier along the way. Also, just any information is welcome!

Edit: accidentally word