how do YOU transition from initial hook to main piece?

It's a little difficult to give any specific advice to a general question. An example might help, but I'll take a guess.

Too much of newbie copywriting resembles a Rube Goldberg contraption of gimmicks. To be any good, copywriters have to give up on the component snap-on gimmick and develop a coherent whole letter.

Your hook should suggest a theme for your whole letter. Each section should support the hook, and the transitions should almost suggest themselves. In other words, never transition from your hook -- your central premise and offer -- elaborate it.

However, on a more basic newbie level there are transition helpers like "In other words" and "however."

Others are...

Better Still
What's in it for you is
Here's why
Consider this

Something like "don't just take my word for it..." can transition to your testimonials or other proof. It really depends on what you've got as to what best to use and how.

The point is flow, smoothness, and coherency. For example, let's say you show someone doing a backflip to get attention (the first section of the copywriter's AIDA formula).

Rookie copywriters botch it ...let's examine how. They append a gimmick like "But wait there's more," and pile on one unbelievable claim upon another. The Better Way: Explain the reason you have a person doing a backflip is the way you tailor pants means change, keys, wallets and costly personal electronics will stay put -- no matter what.

Too many copywriters forget "hooks" are useless by themselves. People who fish know a simple truth. You cast your hook. Once the fish takes the bait, a skilled angler will give the rod a sharp pull to "set" the hook in place. The fish can wriggle free when the hook isn't set.

Setting your hook applies to copy. Fewer fantastic claims, more belief structure. Cast the hook. Then set the hook. Keep the hook throughout the letter, don't transition away. So, for instance with a headline like "Is Your Computer an Overpriced Under-Achiever," then your call to action is "Do it now - before you face your underachieving computer again - call toll free ..."

When you don't do this the flashy, gimmicky, headline gets attention. But the artificial transition gimmick to the loosely related main copy lacks flow and consistency. You can see such swipefile poisoning all over the place, with copy-and-paste sections stitched together by artificial transitions like Frankenstein's Monster. All the pieces are there, but it's a horror show with clearly visible transitions stitching everything together.