The first type are promos where if your bet fails by a certain margin, you recieve a money back refund (usually in the form of a bonus bet).

One of the most common examples of this type of promo occurs in horse racing, where if you back a horse to win and it comes second or third, you would get your stake back as a bonus bet up to a certain amount.

Similarly, these types of promos are widespread in sport, often where if you back a team and they lead at a particular stage of the game (e.g. half time), but then loses, your stake will be returned. 

The other type of betting promotion typically offered by a bookie involves enhanced odds.

For example, certain sports markets are given inflated odds as daily specials, which can be very appealing to punters.

These types of promos tend to reward confidence when betting on a particular horse or sporting outcome, with some extra money in the pocket always appreciated by punters.

With so many promotions on offer at a given time, it's important to not only capitalise on the good ones, but beware the others that aren't worth the trouble.

Over time this will make a big difference in potential profit.