Hi Katarina,
All the answers above are good suggestions. However, all that depends on the location and your industry and economic situation.
Here are my few quick tips what I have learned managing both campaigns over the period of 24 months with budget of 500.000£
One, there is a real difference between campaigns with the traffic being sent to the websites and website aka landing pages with no navigation with one form only something like Unbounce pages. Campaigns with CRO orientated landing pages ( no navigation) like Unbouce were converting much more compared to the campaigns with the traffic being sent to the regular website ( users were able to explore the whole website). What I have learned from that is that you can have on both campaigns a cap on how much you could spend but the same daily amount (daily cap) performed completely different. Campaign with traffic to the general website with navigation needed a minimum daily threshold after ( minimum amount required to be passed) which I have started seeing conversions - so having them limited by daily budget was a real threat to the conversions.
That being said we removed the daily cap for another reason.
We have seen the days ie. Wednesdays where you could spend twice as much on average and have just about some conversions. Comparing that with weekends = two days you could spend the same amount but no conversion at all. That means no days equal the same amount of daily cap as some of them may have traffic spikes.
This is why I am against having a daily cap as long as you really know your particular market. For us having such a bid data turned out to be a real advantage and we were able (based on data) find specific patterns such as conversion by an hour and days.
Taking this further we were bidding on the expensive keywords 15£ per click for the last 12 months having them in an exact match only. We were then able to figure out on average how much we really have to spend - how many clicks to have a conversion which turned out to be 10- 7 clicks.
And yes for your information we have had a daily cap which on average was burned out around 4 pm (unfortunately for enough long time) only to find out that later that our best conversion time was 6-9 pm. I have learned this leaving the daily cap off.
Again that being said we were able to find out all of these insights only by not limiting the daily cap. Some days had 3 times more total impressions and therefore more demand, and therefore more budget was required. Having that in mind I advise you to keep track of daily impressions weekly and monthly and rather than by clicks - measure your impact by a number of conversions per number of impressions in a given day week and month.
Last but not least I haven't detected much of click fraud, but I have installed click guardian on our Unbounce Landing pages. That allowed us to set 2 clicks only from the same IP per day. You can also compare all the conversions coming from specific IP and compare all of them with Click Guardian data.
I can agree with advice being given on the internet by only in case if they are extremely obvious. I have met people from PPC agencies running campaigns with no Click fraud protection, and that is no brainer so, in this case, such advice of having Click Fraud solution is obviously valid at any point of your campaign because if not you can end up having one user clicking 5 times within one day costing you in our case 15£ x 5 =75£ So if your daily cap is 75£ per day what you learning from data is completely nothing.
Hope that helps a little bit