Yooka-Laylee and the Impossible Lair

There are a total of 200 T.W.I.T. coins in the game, five per level. Take note that this is a collectible achievement, so spending T.W.I.T. coins by giving them to Trowzer does not impact this achievement. Also note that for a collected T.W.I.T. coin to count, you must collect it and then complete the level with it collected. If you miss any, and then replay that level to get them, you cannot quit out of the level. You must complete the level.

Normally, if you die after collecting a T.W.I.T. coin before getting to a Checkmate, you'll have to collect that T.W.I.T. coin again. To eliminate the need to do this (and therefore a lot of frustration in some levels), I highly recommend buying and equipping the 'T.W.I.T. Coin Banker' tonic as soon as possible. This is located by the third chapter. Complete the Pagie challenge to lower the land, then head west toward Vendi to collect it. Purchase it and equip it immediately. Its effect is that whenever you collect a T.W.I.T. coin, it stays collected permanently even if you die. It'll lower your quills earned, but this benefit is way more important.

In terms of locating all of the T.W.I.T. coins, some of obvious or easy to find, but many are very well hidden. I highly recommend consulting a guide as you go to eliminate the need to replay all 40 levels to collect all of the T.W.I.T. coins you missed. Below are video guides for all locations. Full credit to the creator of the videos.