Tips for beginner guitarists and bass player to practice together?

Learn guitar playing songs, when you learn musical theory, look for songs that uses that ressource. Guitarquarter has a great list of Easy Guitar Songs For Every Beginner

Try some eazy Blues key of E is easy to learn also Key of A This will help new players to keep to a Beat and there is only 3 chords your new players will have to deal with actualy 4 chords but the 2,3,4 chords are just slideing the same chord up or down.

If the type of music you're playing normally has drums, then I highly suggest getting a drum machine or beginning drummer to play with (or an experienced drummer if you can find one). Learning to be on time together is very important.

Along the same lines, getting an affordable PA system so someone can sing along would help also. Having the vocals really helps keep track of where you are in the song.

The most important, by far, thing to learn is to listen more to the other player than you do to yourself. Learn to adjust your meter, volume, tuning, etc. to match the other player.

Everything else follows from that (and from practicing on your own, of course).

Pick a song in a style that the guitarist can play. Teach the bass player the roots of each chord. Play. As the bass player improves work on playing an actually bass part. If the bass player can learn a few bass parts to a few songs play those songs.