If you're a SMB, you often don't have a lot of time to figure out the optimum bids for your products. However, there is one big mistake that you do want to avoid: do NOT bid so high as to spend your entire campaign budget each day.
For example, let's say you sell guitars and you're willing to spend $100/day on Google Shopping. Let's also assume that you've set up a very simple bidding system: all products receive a $1.00/click bid. If you notice that your daily spend is actually hitting around $100/day, you need to lower your bid.
Why? Because your budget is being exhausted and therefore your products are not active throughout the entire day! Experience has shown us time and time again: if you are spending your entire daily budget (or are consistently within 1-5% of it each day) -- you should either lower your bids (recommended, Method 1 below) or increase your daily budget (Method 2 below).
Method 1 (recommended)
Lower your bids slowly until you see that your daily budget is NOT being exhausted by Google. For the example above, this might take several passes. The guitar merchant might drop his bid to 0.50/click, and then notice that he's now spending about $65/day. That is fine, but he then may try 0.75/click, and notice he's now exhausting his budget again. So he drops it to 0.65, and notices that he's spending about $85-95/day. Perfect! He's almost hitting his budget but he's not quite allowing Google to spend the entire budget.
Our guitar client will now see a couple of positive changes:
Merchant's products are now shown throughout the day
Number of daily clicks will increase (often significantly) enabling merchant to get more people on the site for less money.
Conversion rates will typically maintain the same as before (which begs the question: why were we paying more previously when these clicks are just as good, more plentiful, and cheaper!)
Overall spend can decrease slightly as you're no longer allowing Google to spend your entire daily budget.
If you really don't want to lower your bids, check out "Method 2" below.
Instead of lowering bids the other option is to raise your budget. Obviously, this will require you to spend more on Google. We recommend "Method 1" because most clients in this predicament have a small budget and set their bids too high. However, if the following apply to you, then Method 2 is a viable alternative:
You are seeing good ROAS (no point in spending more if you're not seeing good returns currently)
Your bids are already conservative (aka low)
Your daily budget is low
And of course, you see that Google is consistently spending your entire daily budget
If these apply to you, keep raising the daily budget until you see that Google is unable to spend the entire daily budget. Now your products will show throughout the day. Your spend will increase but your ROAS should remain the same -- you're now generating more revenue because you're maximizing the channel by allowing Google to show your product more frequently.
Don't let Google spend your entire daily budget each day in Google Shopping Campaigns. It's very likely a sign that you need to lower your bids (Method 1, recommended) or increase your daily budget (Method 2).