If you want to be principled:
Big Systematic Official Rules for naming a hydrocarbon based on its structural formula:
- Identify the longest continuous carbon chain. If the compound contains a double or triple bond the longest chain must contain this feature.
- Number the chain from the end which gives the double or triple bond the lowest possible number. If there are no double or triple bonds, number so that alkyl groups or halides get the lowest possible number.
- Number all attached groups using the order from #2.
- Use the appropriate prefix or suffix to name the attached groups (alkyl groups and halides) and multiple bonds.
- Use one word to name the compound. The name of each group is preceded by a numeral indicating its attachment position in the main chain. Alphabetical order is used when more than one group is involved.
- Numerals are separated from words by a hyphen and from other numerals by a comma.
Cycloalkanes:
Aromatics: