Hey, it seems very popular for BlenderArtists users to post to job threads with, “I pm’d you.” If you do this, you should know that other employers may be looking through the job posts scouting for talent. If you only send a private message to the person who posted the job thread, you only have a small chance that he/she will choose you. But, if you publicly showcase your work, you may catch the attention of someone else. If you want to be considered for professional work, get a website; publish samples of your 3D experience and your resume. Make it easy for employers to find you.
To the contrary, the recommendation here is that you send a PM (or email, or whatever was specifically asked for) to the person who made the job posting. There’s really no need to make a post that says you sent the PM.
Show your work publicly using the Artwork forums (that’s what they’re there for).