There are only about 4 things you need to know about semi-log plots, so at the risk of repeating myself…
If you have data that follows an exponential model, the semi-log plot will appear linear.
If the semi-log plot appears linear, you have data that will follow an exponential model.
For 𝑦=𝑎𝑏𝑥, the corresponding linear model has slope log𝑛𝑏 (where 𝑛>0 is whatever is the ratio between your equally spaced vertical axis tick marks)
For 𝑦=𝑎𝑏𝑥, the corresponding linear model has initial value log𝑛𝑎 (where 𝑛>0 is whatever is the ratio between your equally spaced vertical axis tick marks)