Don't drill for the love of all that is good and holy! If you can't weld, you shouldn't be using a drill on your frame. As a matter of fact, if you want to drill and you can't weld, give me your drill.
*Don't drill a T-style bracket of universal motor mount - get the U-style bracket.
*Don't drill for the china girl throttle - pull that pin out with a pair of pliers, it'll be fine.
*Don't drill your chain tensioner - operative word being TENSION.
Speaking of tensioners - if you use one and your chainstay (rear bottom tube on the left side) tapers, get heavy duty duct tape (don't skimp, get the expensive stuff, it'll save you a whole rear wheel) and wrap where your tensioner is going to be, as well as a couple inches to either side. Put it on thickest where the taper is the smallest, and blend it smoothly as possible. Do not rush it - put it on seamless with no bubbles, hit it with a heat gun or a hair dryer for no more than a minute to dry it, let it cool for as long as you can stand so your glue doesn't slide and put your tensioner on now.
When there's a taper, the tensioner likes to travel in and out of the frame (most often inwards), esp. with the two bolt single plate setup. You're not drilling because it's downward pressure against the whole at its weakest point.