A great way to get noticed is by patronizing other streams. Now, this isn’t to say you should hop from stream to stream and advertise. In fact, that's a great way to get reported. While we certainly want to encourage experiencing as many diverse streams as possible, be conservative with your efforts. Take your time.
When you’re there, certainly greet the streamer and any other names in chat you recognize. You’d be surprised how a simple greeting can result in new friends, renewed friendships, and new eyes on you. If you have been to this stream before, you may even get a nod from the streamer yielding new follows. Just be yourself and engage.
While chatting it up, you may be tempted to promote yourself. Unless specifically requested by the streamer/moderators, doing so will come across as an advertisement. This is not the way to gain new viewers. Of course, if the streamer knows/recognizes you, they will probably want to know what you’ve been up to. In this situation, by all means share but keep it short and sweet. No one appreciates walls of text in chat.
Raiding. While intentions when raiding on Mixer are (hopefully) positive, the intended stream may not welcome it. If you typically see this streamer live at the same time as you, their stream could be ending as well. Unless you have permission to raid (via standing approval, profile text, etc), it may be best to move on. Networking with other streamers starts and ends with the integrity of your relationship. Do right by them and they may return the favor.