Confessions of a researchaholic

Are you a paper committee paper or journal associate editor (AE) who want to increase the likelihood of reviewers responding positively to your invitations?
Here are some tips based on my own experience:

Instead of a machine-generated generic email, craft a custom message telling the candidate reviewer why you think they are a good fit for the paper, such as their background respect to the topic or specific components of the paper.
You should have this information already when deciding to invite that particular reviewer.

Add some personal greetings such as if the reviewer has a recent job change or life event, a new paper, or someone you both know, which could be found on their social media or personal website.
Do so particularly if you know the reviewer (or someone close to them like their collaborator/advisor) personally.

If you already read the paper, provide some estimation of the time commitment required for reviewing the paper, e.g., “I think it will take you about 2 hours to review this paper”.

If you have accepted review requests from that reviewer in the past, mention this as well as a hint of reciprocity.
This is another reason to accept review requests if you have the bandwidth.

Throughout my research career I have been very conservative in recruiting PhD students, especially for those whom I would be the (de facto) advisor.
(I am a bit more relaxed for hiring interns as the collaborations are shorter term and thus the risks are lower.)
I prefer to have deep involvement for each student and project, and the cost of having a student not suitable for independent research is higher than the risk of occasionally passing on a top candidate.

However, there are other professors/researchers out there who have been very successful in managing large groups.
So definitely go for that if your style is like a VC incubating startups, you have enough funding, and your projects require teamwork (e.g., one student probably is not going to build a new operating system or programming language).

Reviewing papers can take a lot of time, but also has the following benefits:

It is a good way to build reputation and relationship with the research community, especially if you can do a good job and write a good review on time and participate in the discussion phase to help reach the final decision if that is part of the review process.
If you submit to a venue, it is only fair to review for that venue, especially if you have complained that your submissions have not received good/fair reviews due to lack of expertise or efforts from the reviewers.

It is a good way to learn about the latest research in the field, especially if you are assigned to review papers outside your main research areas.
Writing a good review (see above) requires deep enough understanding of the paper beyond the usually more cursory catching up of published papers.

It is a good way to learn how to get your own submissions accepted in the future by looking at how decisions are made and what the reviewers are looking for.

Accept only reviews that you think you have the time and expertise to do a decent job, and do not feel bad about declining reviews otherwise, preferably within a few days of receiving the request with suggestions for alternative reviewers so that the organizers can find replacements in time.
Other things being equal, prioritize review requests from higher-quality venues for which your reviews would tend to make a relatively bigger impact.