1). Get familiar with aircraft log book entries, and maintenance requirements.
2). Contact whoever will maintain your aircraft after buying.
3). Do not part with money/commit to buy until that guy has inspected it.
Many aircraft for sale can be rejected on information YOU can obtain, and show to your chosen mechanic. One cannot be sensibly bought without him examining it in person.
You'll need insurance before buying. You buy "Free of all debt".
Consider buying a share in an aircraft. Seriously consider renting until you have over 100 hours logged. Consider also Annex1 aircraft.