The two biggest mistakes people make are:
Surface prep. lots of sanding, and a very good scrub in Alkaline Cleaner
Contact: don't just hang on a hook, has to be a tight, firm connection! either friction press fit or even better, threaded. I screw my pen pieces onto my jig which is threaded in M10 and M12 to take my body and lids. whole jig is aluminium, keep in mind the threads are protected when screwed together and don;t anodise, allowing you to use them over and over. or if you want to splash out then grade 2 Titanium. (note if you actually want to anodise titanium pretty colours, then use grade 5 oppose to 2)
Get your head firmly around those two key pieces and the rest of it is trivial. too much current it will turn a yellow hue, which rarely poses a problem if you're dying it. not so great if you planned on leaving it clear... too little current will give poor results. 145 to 175ma per square inch. don;t forget to factor in the inside of the aluminium if that too is exposed to the electrolyte.
Cathodes should always be at least twice the size of the piece you are anodising. I use lead flashing.
all my plating tanks are now in 5 Litre buckets with sealable lids. actually takes up less room than the brush plating gear and is safer in my book, with suitable ventilation / extraction. Playing with potassium cyanide for brush plating gold for mediocre results wore thin pretty quickly. At least this way when you;re finished you can clip on the lid and put your chrome tank on the shelf
