Shirlene posted a link to a video with good tips here is the link to her post.
Alice

Also I've found that if you move your spool of metallic away from the machine (I put mine on my seperate thread stand and allow it to unwind from a distance it seems to work like a charm. Good luck, I use the metallic needle, slow speed and a little distance on the thread and it works great.

Only, ever, use Janome or Organ needles with your Janome machine.The shanks on the Schmetz, and other brands, are longer. You won't get a good result.
I have found that the Madeira metallic threads is one of the best to use with the MC300E.
I don't know which brand of thread you are using, but they are not all the same. Some threads are very bad.
Ricky

you could get the same affect try putting the metallic thread in the bobbin.

I am fairly new to embroidery myself but I have used metallic in some of my Christmas things and have had great success. I have found the most important thing is to have the reel upright and far away. I have my ordinary sewing machine behind my embroidery machine and I put my thread on the spool of my sewing machine. By the time the thread reaches the embroidery machine the kinks have gone. Hope this helps. Sarah.

I used to DREAD using metallic thread, because I didn't have good luck with ANY of them. I now keep all of my metallic threads in a zip-loc baggie that I sprayed waterproofing spray in (just a quick "spritz"). I take the threads out about every 6 months and give the baggie another spritz. Before using the thread, I'll dab it with a paper towel, just to make sure there is no "moisture" on the spool, and thread my machine as usual. No more special needle, slowing the speed, or even taking several deep breaths, hoping for good results.
I hope this helps....(I find the waterproofing spray near the shoes at stores like Target or WalMart.)

I too have a 300e. I use only schmetz needles and have for the most part OK luck with metallic. My husband has taken my 300e back with him (he works out of town) to make Shirlene's little stockings for the neighbor's gifts. We are using metallic thread. I place the thread on the table in front of the machine not on the peg (kinks too much on the horizontal peg) and then AROUND the handle and then through the thread guides. All the kinks are gone before it reaches the first guide. We did have one break in 30 minutes but just rethreaded and kept going. We did not slow down the machine although I told my husband it was an option if he had problems. Becky

Pull your thread thru a packing peanut first with a regular needle. Then thread embroidery needle. Works great. No thead breaks.

You may have to lower your top thread tension down just a bit. Then test.
Try a size 80/12 Metallic needle.

Put your thread on a seperate Thread stand behind or in front of your machine.

Some Metallic threads are better and smoother than others.

I like Kingstar metallic thread.

EastWitch2

I have a brother and was having the same problem. It turned out that the thread is getting "twisted as it curls off of the spool. What I do (and it can be a pain) is hold the spool on a pencil were the thread pulls off of the side instead of the top of the spoool. No twists in the thread, no more thread breaks.

undecided, I don't have trouble with metallic threads - I use a metallic needle (but don't feel it is necessary all times) - I put a net around the thread - I don't adjust my machine - I do use a thread stand (for all my embroidery) and I just enjoy stitching with metallic thread. *4U