Deciding on the mix of influencers for campaign planning depends heavily on the goals of the campaign, the target audience, and the budget available. Here are some best practices to consider:

1. Define Your Goals: Understand what you aim to achieve with the campaign. If you want to drive mass awareness, mega-influencers may be most suitable as they have large audiences. If you want engagement or conversions, micro-influencers are often better given their higher engagement rates and niche audiences.

2. Understand Your Target Audience: Know who your target audience is and determine which influencers they are likely to follow. If your target audience is highly specialized, a micro-influencer who is an expert in that niche could be your best bet.

3. Consider Your Budget: Influencers with more followers often command higher fees, so align this with your budget. Micro-influencers can be more affordable and yield better ROI, particularly for small to medium-sized brands.

4. Balance The Mix: Think about using a mix of micro, macro, and mega-influencers. This can provide broad reach (from macro and mega influencers) and high engagement (from micro-influencers).

5. Track Performance: Use an influencer marketing platform like Flinque to track the performance of your influencers and campaigns. This can help you refine your mix of influencers for future campaigns.

Remember, the mix of influencers will vary from campaign to campaign, and there is no one-size-fits-all answer. Use data to make informed decisions and continually test and refine your approach.