Here is one simple step a recruiter told me about several years ago: Be sure your email signature reflects your profession. I'm in the kind of work where I'm actively looking for clients. So for me, it makes sense to have an email signature that reflects the kind of work I do.
If you already have a job in your field, but you're looking for a better opportunity, be sure and list your current job title and industry on your email signature. Many people do this automatically for their professional email accounts. But list your title and/or profession on your personal email as well. I don't recommend listing your company name on your personal email (some people do, but just keep in mind your liability in representing your company with whatever you write in that email). It's most effective just to list your industry. For example, My Name, Marketing Manager, IT.
This is a very easy way to keep your professional interests in front of people. You never know what connections might develop from this: for you in networking; for your company in referrals; for people needing your service or products.
But what if you're looking for the kind of work you don't have yet? I think this email signature strategy could still be effective.
Do you have a blog that reflects the field you're trying to get into? If not, you might want to consider it. Blogs are a great networking tool and a way to show your insights and expertise - even in a field you aren't working in yet. If you're interested in that field, you already have things to say about it. Writing a blog also gives you an incentive to do further research and keep up with current news in your target industry. You can also make behind-the-scenes connections by inviting people in the industry to guest blog for you, or by interviewing them for your blog. Blogging will put you in front of people with similar interests and will show recruiters that you are already engaged in this field. Your blog will give hiring managers a sneak preview of what it will be like to work with you.
If you do have a blog - or when you create one - you can list that in your email signature. Let's say you want to get into the oil and gas industry. You would start a blog about this industry. Then your email signature would look like this: My Name, Oil and Gas Blogger, Contact Info (including the link to your blog).
Set up your email signature block, through your email program, so that it comes up automatically, every time you send an email. Resist the urge to censor your email signature. Often, we think if we're just emailing a friend or family member, we don't need that signature. But it's always helpful to keep your field of interest in front of people - even the people who know you well. You never know when something will spark and they will connect you with someone else in your field.
If you don't have a blog and don't plan to create one, you can still benefit from your email signature. Think creatively. Put yourself in a recruiter's shoes - what would get their attention and help them notice that you are a candidate for their open job? You might put "XYZ Industry Candidate." If you've just graduated from school, you could list under your name: "2017 Graduate - ABC University - Chemical Engineering." (Be sure and list your school - people love their alma maters and it's a great conversation starter, a mutual connection.) If you don't have a job right now, you could even write beneath your name: "Seeking XYZ position" or "Desiring to work in the ABC industry." Just keep it professional - think about how it will appear to a recruiter or potential employer.
Your email signature is your advertising marquis. With a little creativity and persistence, you can use the random emails you send every day to promote yourself as a candidate for a job that someone, somewhere knows about.