Boy, you are surrounded by a cloud of germs, aren't you? Have you talked
to you rheumatologist about how to manage the infection issue?
There are things you can do to be as healthy as you can do while not counteracting the effects of Enbrel. Eating a well-balanced diet with lots of fruits and vegetables, cutting down on junk, getting plenty of rest (yes, I know - as a mother of three small children, that's a challenge). You don't mention what kinds of illnesses you get, but I've been on Enbrel and I suspect that a fair number of them are sinus infections due to the increased mucus production and inflammation of your sinuses. There are definitely things you can do to stay ahead of this particular problem and in a neat coincidence, my latest post was about managing side effects of medication, including tips related to taking Biologics. You can read it here. Aside from frequently using hand sanitizer, you may be able to talk to your boss about protective measures, such as wearing vinyl gloves or a mask, although given that you're in a customer service job, they may not agree to that. Again, your rheumatologist should be able to give you some tips on how to manage infection risk in public.
You may also want to consult a doctor of naturopathy for supplemental alternative treatments that won't interfere with your medication. Check your Yellow Pages to see if there's one near you. If you live in a large urban center, there may be a naturopathy college somewhere where you can be seen by a student (supervised by a naturopath, of course) for less money.
Lastly, based on my own experience, I found that when I was on Enbrel, I was sick quite a lot, as well. About a year and a half ago, I switched to Humira and am doing much better - I feel healthier and am not sick nearly as often. At some point, if the side effects of the medication you're taken become intolerable, you can consider discussing switching meds with your rheumatologist. The whole point of these medications is to help you get back to your life and if you're sick all the time with side effects and not functioning well in your life, then it's not working