When investing in dividends ETF, should I invest in small amounts consistently or a single lump-sum amount when possible to earn dividends?

If you already have the lump sum with you, its better to go one shot than do DCA. If you dont have the lump sum then buy whenever you can accumulate enough to justify your transaction costs. DCA is simply a way for people with less control/discipline or no lumpsum to invest without thinking much about.

Take a look at the ETF price history and valuation to decide if the ETF is overpriced currently. If it is overpriced/overvalued, both lumpsum and DCA dont make sense...why buy something when its expensive?

Hello!

I would personally invest in small amounts consistently as it is a form of Dollar Cost Averaging as mentioned by Sandra. It would help to reduce the possibility of buying at the highest price. This also means that you will be buying the ETF at an average price. Buying a lump-sum amount would have a higher risk of buying the ETFs at a higher price as compared to buying it consistently, thus i personally would choose to buy it consistently as compared to lump sum.