Some pro tennis players are hailed as great 'serve and volley' exponents, and this usually means they manage to place a larger percentage of powerful first serves in play than others might. Equally, it's not unknown, even for top players, to have a much weaker second serve, perhaps aiming for safety and simply 'getting it into play'.
This can be even more of a truth for club players. Yet, a fair number of coaches will recommend that you base your game around a second serve, simply because that's the more likely scenario you will be faced with. Before we look at some specific tips, it's useful to play the occasional friendly match where only a single serve is allowed. This will help you to drill a reliable serve, which can be used as a constant back-up to those booming first serves that don't quite hit the spot.
Coaches reckon that a second serve should be around two-thirds of the pace of your first, allowing for more control. Now that you are relying less on pace, it's time to focus more on spin and placement. Make sure that you make best use of spin to give you an advantage. This means that you are likely to use it to take the ball further away from your opponent, either wider off the court in an outside corner, or away from their stance if you go down the centre.
The aim is to have them on the stretch when they return, given that the slower pace will probably allow them a few more moments to get into position and execute their shot. Within these guidelines, aim also to learn where your opponent likes to be, their preferred choice option, and aim to place the second serve away from that. Of course, you also need to introduce an element of variety. Constantly aiming for the same targets reminds us of the old slogan: 'They who always do what they always do, always get what they always get'!
As you practice and groove your second serve, building up consistency, then this allows more confidence to try things with your first serve. Remember also that you are aiming to be best equipped to handle the reply your opponent makes, so placement is also about thinking ahead and aiming to force returns to allow you to play a comfortable next shot - and hopefully it's a winner.