Contamination of the blood sample seems to be the main reason for the error readings. The smaller the blood sample (and the Plus can use a tiny bubble of blood), the more likely it is to be contaminated by sweat or oil on the skin. Even with practice I still get about five times as many error readings with the Plus than I did with my old Pro. Here is what I do to minimize error readings:

1) Use a fatter-gauge lancet than the fine (30-gauge) one that typically comes with the meter. You need to produce a droplet of blood sitting proud of the skin that is roughly 3mm (1/8 inch) in diameter. If you don’t get that nice big droplet after about 10 seconds, do another poke adjacent to the first rather than squeezing more and harder. It is likely that you missed a bigger capillary and that the tiny hole is already clotting shut
2) Your blood sample should form a nice viscous droplet standing up on the skin. If the sample is thin and watery looking, do not waste a test strip. It is likely to be contaminated with sweat or the athlete is overly hydrated.
3) Set the depth of the lancet penetration to maximum on the lancet holder. Usually there is a scale of 1 to 5. I always dial it up to 5. You need to hit a decent-sized capillary or you will not get enough blood.
4) If you plan to self-test you will need to poke a finger as described below.
5) During a finger poke, once the blood droplet has formed, I (the sample taker) use my little finger of the hand holding the meter to steady my hand against the athlete’s hand. For an ear poke, I brace my forearm against the athlete’s shoulder. You need something to stabilize against: The athlete is likely to be shaky, and even tiny tremors in your own hands can cause you to miss the droplet or go too deep and touch the skin.
6) I prefer to poke earlobes rather than fingers. Fingers, especially of climbers and skiers, tend to be callused, making striking a motherlode capillary nearly impossible. Plus, hands tend to sweat a lot, making contamination more of a problem. I have yet to meet anyone with calluses on their earlobes. The skin is thin, and the lobe is highly vascularized. Earrings should be removed before the test as they can get in the way. I find that I get bigger droplets with smaller-gauge lancets when using earlobes. The disadvantage is that you can’t self-test on an earlobe.
7) If it is cold out it can be very hard to get a good sample from a finger. In cold conditions blood flow to your extremities and especially fingers is reduced. Warm fingers are a must for this test so either pre-warm them in gloves or by windmilling the arms vigorously till the fingers turn red. Otherwise you’re are not going to get enough blood for a good sample. Some people suffer from a common condition called Reynaud’s Syndrome where the finger capillaries shut down with very little provocation. I’ve never heard of the earlobe being affected this way making this another reason to use that appendage.
8) Have all your gear: lancet holder, meter, strips, paper tools laid out where they are easily reached during the test. I use a small towel to spread things out on. Rarely will you have a table when testing outdoors so get creative. A car hood, tree stump or log a big boulder can often be repurposed to a table.