Grinner Knot -

This is a multi purpose knot that is more securely clinched than it's relative blood knot. It's use is attaching swivels, lures, and hooks to the main line.
Assist its formation by pulling down to the base

Half Blood Knot -

One of the easiest knots to perform is the half blood knot. It is also one of the safest knots to have when tying to singular hooks, swivels and lures. If you look at the design of the knot, you can see that if tension is applied to the hook, the coils actually exert more pressure on the line, preventing it from slipping off your hook.

The knot is tied by passing the line thru the eye of the hook, wrapping the tag around the main line 4-6 times, then passing the tag back thru the first loop made around the eye of the hook. The finer the diameter of the line in relation to the diameter of the hook eye, the greater the number of turns (up to six) that should be made.

If you really want to be fussy, take a cigarette lighter and melt the cut tip of the line (the tag) so that a small ball of monofilament forms. If your not careful, the heat of the lighter could degrade the strength of the knot and line on the hook. I usually don't worry about this. Knots these days have been designed to cater for most situations of fishing.