Driving onto wood blocks is the easiest and most cost effective way and its the tried & true method used by tens of thousands of RVers for many, many years. If you need to get higher than about 3-4 inches, you will need a series of boards so you can climb them like stair steps rather than all at once. A longer board, maybe two feet long than the tire footprint, will let you step up a couple inches and the additional board(s) can be placed on top of that, further back. The board the tire actually sits on need be only large enough for the contact area of the tire, typically no more than 12-16 inches long and 7-8 inches wide.
When using boards, make sure the tire rests fully on the board and does not hang over on the edge or end. The tire is designed to roll over raised edges but not to sit on one for extended periods.